4.10 HYDROLOGY AND WATER QUALITY · 2011. 10. 18. · 4.10 Hydrology and Water Quality SANDAG 2050...

4.10 Hydrology and Water Quality

SANDAG 2050 RTP/SCS EIR 4.10-1 JuneOctober 2011

4.10 HYDROLOGY AND WATER QUALITY

This section presents existing conditions, evaluates the impacts to hydrology and water quality associated with implementation of the 2050 RTP/SCS and identifies mitigation measures for significant impacts. The information presented was compiled from multiple sources, including Project Clean Water (PCW), the Regional Comprehensive Plan (RCP), and the Regional Water Quality Control Board (RWQCB). 4.10.1 EXISTING CONDITIONS

Hydrology

Watersheds and Hydrological Characteristics

The San Diego region is divided into two hydrologic regions by the northwest-trending Peninsular Range. On the gently sloping western side of the range is the San Diego Hydrologic Region, and on the steep eastern side is the Colorado Hydrologic Region. Each hydrologic region is further divided into hydrologic units (HUs) that are defined as an entire watershed of one or more streams. Each HU is divided into hydrologic areas (HAs), which are the major tributaries and/or major groundwater basins within the HU, and further divided into hydrologic subareas (HSAs), which are major subdivisions of HAs including both water-bearing and non-water-bearing formations. Surface waters in the San Diego region include the ocean shoreline, bays, lagoons, lakes, reservoirs, streams, and rivers (Figure 4.10-1). Forecasted 2050 RTP/SCS associated development spans both the San Diego Hydrologic Region and the Colorado River Basin Hydrologic Region. The San Diego Hydrologic Region includes 11 HUs, and the San Diego region includes all of the Carlsbad, San Dieguito, Peñasquitos, San Diego, Pueblo, Sweetwater, and Otay watersheds; the majority of the San Luis Rey watershed; and portions of San Juan, Santa Margarita, and Tijuana watersheds. All of the watersheds in the San Diego Hydrologic Region ultimately drain to the Pacific Ocean. Figure 4.10-2 shows the watersheds and the groundwater basins. Characteristics of each watershed in the San Diego Hydrologic Region include the following (refer to Table 4.10-1 for a complete 2006 Clean Water Act Section [CWA] 303(d) list for all of the watersheds):

• The San Juan watershed (HAs 901.1 to 901.5) covers approximately 496 square miles of which only 150 square miles lie in the northwest portion of the San Diego region. Most of the watershed lies within Marine Corps Base Camp Pendleton (MCBCP) in Orange and Riverside counties. Two of its hydrological areas are within the San Diego region (San Onofre and San Mateo). Major stream systems include the San Onofre, Las Flores, and Aliso Canyon creeks, which are usually dry from July through November. Topography varies from Pacific Ocean coastal plains to the Santa Margarita Mountains (over 2,000 feet above mean sea level [AMSL]). Various wildlife species use the undeveloped, low-lying creeks and streambeds as corridors to range freely within MCBCP and eastward into higher elevations. This portion of the San Juan watershed is largely undeveloped because of federal ownership. The land uses include open space, military base operations, and agriculture. Past water quality monitoring has indicated that the region’s surface waters are high in total dissolved solids (TDS) (PCW 2010). San Mateo Canyon HA at the San Mateo Creek outlet to the Pacific Ocean is on the 303(d) list impaired for total coliform (SDRWQCB 2006).

• The Santa Margarita River watershed (HAs 902.1 to 902.9) encompasses approximately 750 square miles of which only 200 square miles lie in the northern San Diego region. Most of the



flow from the Santa Margarita River main stem is within the San Diego region and traverses through unincorporated areas, the community of Fallbrook, and MCBCP. The lower river and estuary at the Pacific Ocean coast remain less developed than other municipal coastlines to the south and, as a result, support abundant habitat and wildlife. Presently, the Rainbow Creek tributary is on the 303(d) list for an impairment of iron, sulfates, and TDS (SDRWQCB 20092006). The lower Santa Margarita River is listed on the 303(d) list impaired for enterrococcus, fecal coliform, phosphorus, and total nitrogen (SDRWQCB 20092006). These water bodies have been subject to excessive inputs of nutrients from a variety of sources including agriculture, nursery operations, municipal wastewater discharges, urban runoff, septic systems, and golf course operations (PCW 2010). Other serious water quality and environmental concerns in the watershed include excessive sedimentation from development and agricultural areas, groundwater degradation and contamination with nitrates and other salts, habitat loss, channelization, flooding, and scour (PCW 2010).

• The San Luis Rey River watershed (HAs 903.1 to 903.3) is the second largest HU in the San

Diego region (558-square-mile drainage). Situated in the northwestern portion of the San Diego region, the basin has two major surface waters, the San Luis Rey River and Lake Henshaw, and is divided into three HAs: the lower San Luis, Monserate, and Warner Valley. Roughly one-fourth of the land area in the watershed is located west of I-15, where land uses include open space/undeveloped, residential, commercial/industrial, and agricultural. East of I-15, most of the land is owned and managed by government agencies (county, state, and federal), special districts, and tribal governments. The predominant land uses are open space/undeveloped and agricultural. Unlike most major rivers in Southern California, the San Luis Rey River has undergone relatively little channelization (PCW 2010). The only significant segment of the river that has been channelized is within the City of Oceanside where it then drains into the Pacific Ocean. The lower San Luis Rey River is on the 303(d) list for an impairment of chloride, enterococcus, fecal coliform, phosphorus, TDS, total nitrogen, and toxicity (SDRWQCB 2009).

• The Carlsbad watershed (HAs 904.1 to 904.6), extending from the headwaters above Lake

Wohlford to the Pacific Ocean, is approximately 210 square miles in area. Within the watershed there are four major roughly parallel HAs: the Buena Vista, the Agua Hedionda, the Batiquitos, and the San Elijo. Each HA drains into the Pacific Ocean through creeks and rivers to discrete coastal lagoons. There are also two large water reservoirs, Lake Wohlford and Dixon Lake. Approximately 48 percent of the Carlsbad watershed is urbanized and its population ranks it as the third mostly densely populated in San Diego County (PCW 2010). As a result of this high urbanization, many of the water bodies are experiencing impairments to beneficial uses. The coastal lagoons represent critical regional resources that provide freshwater and estuarine habitats for numerous plant and animal species. Effective planning measures will be needed to prevent this rapid development from further degrading water quality in this region of San Diego County (PCW 2010).

• The San Dieguito River watershed (HAs 905.1 to 905.5) comprises a drainage area of approximately 346 square miles in the west-central San Diego region, with most of the watershed (79.8 percent) situated in unincorporated jurisdiction that is mostly vacant or undeveloped (54 percent) (PCW 2010). Extending from the Volcan Mountains to San Dieguito Lagoon at the Pacific coastline, several natural areas within the watershed are sustained that include the San Dieguito River Park; San Dieguito Lagoon; and three water storage reservoirs— Lake Hodges, Lake Sutherland, and Lake Poway. Ocean waters along coastline at the mouth of the San Dieguito River are associated with elevated coliform bacteria. San Dieguito Lagoon is especially sensitive

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to the effects of pollutants and oxygen depletion due to restricted or intermittent tidal flushing (PCW 2010). Several of the inland surface waters bodies are 303(d) listed for various impairments. In the absence of a comprehensive watershed planning effort, large-scale future development may exacerbate current water quality problems and create additional beneficial use impairments (PCW 2010).

• The Los Peñasquitos watershed (HAs 906.1 to 906.5) drains a highly urbanized region located almost entirely west of I-15 in the coastal portion of the San Diego region. The major receiving waters, Los Peñasquitos Lagoon and Mission Bay, are both fragile systems that support diverse native fauna and flora and are especially sensitive to the effects of pollutants due to restricted or intermittent tidal flushing (PCW 2010). Los Peñasquitos Creek drains approximately 100 square miles that discharge into Los Peñasquitos Lagoon, which is impaired for sedimentation. Much of Mission Bay is adversely affected by nutrients and coliform bacteria from urban and agricultural runoff and sewage spills. Tecolote Creek is impaired by a host of pollutants including coliform bacteria, trace metals, nutrients, turbidity, and toxicity (SDRWQCB 2009).

• The San Diego River watershed (HAs 907.1 to 907.4) is the second largest HU in the San Diego region (approximately 440 square miles), hosts the highest population (approximately 475,000) of the region’s watersheds, and is approximately 58.4 percent undeveloped in the upper, eastern portion of the watershed (PCW 2010). Five reservoirs in this watershed supply water to as many as 760,000 residents in the region. The Cleveland National Forest, Mission Trails Regional Park, and the river floodplain near Lakeside represent three important undeveloped areas that host a wide variety of intact habitats and endangered species (PCW 2010). Beach postings and closures from elevated bacteria levels at the mouth of the river have been attributed to urban runoff and sewage spills (PCW 2010). Famosa Slough, near the mouth of the San Diego River, contains extremely productive wetland habitat (PCW 2010).

• The Pueblo San Diego watershed (HAs 908.1 to 908.3) is the smallest HU in the San Diego region (approximately 60 square miles), is the most densely populated (approximately 500,000), and is largely developed (about 75 percent) (PCW 2010). A relatively large percentage of land is used for transportation corridors and highways (PCW 2010). The creeks in the watershed are highly impacted by urban runoff, and Chollas Creek and the mouth of the creek in San Diego Bay are listed as 303(d)-impaired water bodies for various trace metals parameters and aquatic toxicity (PCW 2010). San Diego Bay, which receives runoff from this watershed, has five locations that are impacted by runoff from the Pueblo San Diego watershed and have been identified as hot spots by California’s Bay Protection Toxic Cleanup Program (PCW 2010).

• The Sweetwater River watershed (HAs 909.1 to 909.3) drains approximately 230 square miles to San Diego Bay. More than 86 percent of the watershed is within unincorporated jurisdictions. The most important watershed issues are related to the protection of municipal water supplies, and the protection and restoration of sensitive wetland and wildlife habitats (PCW 2010). The upper watershed contains large undeveloped areas within the Cleveland National Forest and Cuyamaca Rancho State Park, and the Viejas Indian Reservation. Unincorporated rural and suburban communities characterize the central part of the watershed. The urbanized lower portion of the Sweetwater River watershed contains portions of several cities including San Diego, National City, Chula Vista, La Mesa, and Lemon Grove. The Loveland and Sweetwater reservoirs, and the San Diego Bay shoreline are 303(d) listed.

• The Otay River watershed (HAs 910.1 to 910.3) covers approximately 160 square miles in the southwest San Diego region and consists largely of unincorporated area. The predominant land



uses in the watershed are open space (67 percent) and urban/residential (20 percent) (PCW 2010). Upper and Lower Otay Lakes provide potable water supply and important habitat (approximately 36 square miles are part of the MSCP. Serious water quality problems are limited to the presence of elevated coliform bacteria in the Pacific Ocean receiving waters near Coronado (PCW 2010). In the absence of effective watershed-based management, the natural resources of the Otay River watershed may be significantly degraded (PCW 2010).

• The Tijuana River watershed (HAs 9011.1 to 911.8) drains a region of approximately 1,750 square miles and is probably the most severely water quality-impacted watershed in the San Diego region (PCW 2010). The Tijuana River watershed is classified as a Category I (impaired) watershed by the State Water Resources Control Board (SWRCB) due to a wide variety of water quality problems from U.S. sources (mostly nonpoint agricultural) and Mexican sources (large variety of point and nonpoint). The Tijuana Estuary, a National Estuarine Sanctuary that supports a variety of threatened and endangered plants and animals, is threatened by inflows from the Tijuana River containing high concentrations of coliform bacteria; sediment; trace metals (copper, lead, zinc, chromium, nickel, and cadmium); polychlorinated biphenyls (PCBs); and other urban, agricultural, and industrial pollutants (PCW 2010).

The Colorado Hydrologic Region has small portions of five HUs located within eastern part of the San Diego region. These units include the Anza-Borrego watershed, which is the largest hydrologic unit, covering about 80 percent of the desert portion of San Diego County and extending into Imperial and Riverside counties. Portions of the Clark, Whitewater, and West Salton watersheds are located at the extreme northeast corner of the San Diego region. The Imperial watershed is located at the southeast edge of the San Diego region and extends into Imperial County. Water is limited in all of these areas. The surface water that intermittently exists flows toward the Salton Sea and the Colorado River. Average annual precipitation for the Colorado Hydrologic Region ranges from less than 3 inches along the eastern boundary, near Imperial Valley, to 25 inches in the mountain divide between the Salton Sea and Pacific Ocean drainages. Runoff occurs from winter precipitation especially in the higher elevations and from summer thunderstorms. Approximately 98 percent of the land uses located within the San Diego region portion of the Colorado Hydrologic Region is parkland, undeveloped land, or used for agriculture. The remaining portions are sparsely populated with single-family residential units, and a small amount of other uses (County of San Diego 2009). The Colorado River Basin Regional Water Quality Control Board (CRBRWQCB) divides the Colorado Hydrologic Region into seven major planning areas based on economic and hydrologic characteristics. Only three of these planning areas lie within the San Diego region: Coachella Valley, Anza Borrego, and Imperial Valley. The other four that fall outside of the San Diego region are Lucerne Valley, Hayfield, Salton Sea, and the East Colorado River Basin. Characteristics of each of the three Colorado Hydrologic Region planning areas in the San Diego region are described below (refer to Table 4.10-1 for a complete 2006 CWA 303(d) list for all of the watersheds):

• The Anza Borrego Planning Area includes the Clark, West Salton Sea, and Anza-Borrego HUs. It comprises 1,000 square miles, mostly within the San Diego region and Imperial County, with a small segment in Riverside County. Elevations range from 230 feet below sea level at the Salton Sea to over 6,000 feet along the western boundary. The principal communities in the planning area are Salton City and Borrego Springs. Drainage flows to the Salton Sea except for two small areas of internal drainage in Clark and Borrego valleys in the northwest corner of the planning area. Average annual precipitation ranges from less than 3 inches along the eastern boundary, near Imperial Valley, to 25 inches in the mountain divide between the Salton Sea and Pacific Ocean drainages. Runoff occurs from winter precipitation especially in the higher elevations and



from summer thunderstorms. Perennial flow includes reaches of Coyote Creek and San Felipe Creek.

• The Coachella Valley Planning Area contains the Whitewater HU and the East Salton Sea HU. It lies almost entirely in Riverside County and covers 1,920 square miles in the west-central portion of the Colorado Hydrologic Region. Only a small southernmost portion lies within the San Diego region. Elevations range from over 10,000 feet in the San Jacinto Mountains to 230 feet below sea level at the Salton Sea shoreline. The higher elevations of the San Bernardino and San Jacinto mountains have evergreen forests with perennial streams. A contrasting scene is presented on the Coachella Valley floor where the land contains desert vegetation, except where the land has been irrigated with pumped groundwater or with imported Colorado River water. Average annual precipitation ranges from less than 3 inches in the valleys to 40 inches in the San Bernardino Mountains. Seasonal snows fall on the higher elevations in the San Bernardino and San Jacinto mountains. In the valleys, precipitation from summer thunderstorms often exceeds that of winter. Runoff resulting from rains and snowmelt at the higher elevations is the major source of groundwater replenishment. Perennial streams include the upper reaches of the San Gorgonio and Whitewater rivers, and Palm Canyon, Tahquitz, Snow, Deep Canyon, Chino, and Andreas creeks. The Whitewater River is the major drainage course in the Planning Area. There is perennial flow in the mountains, but because of diversions and percolation into the basin, the river becomes dry further downstream. The constructed downstream extension of the Whitewater River channel, known as the Coachella Valley Storm Water Channel, serves as a drainage way for irrigation return flows, treated community wastewater, and storm runoff. There is one relatively large surface water impoundment. Lake Cahuilla, at the terminus of the Coachella Canal, serves as a storage reservoir to regulate irrigation water demands and is also used for recreational purposes.

• The Imperial Valley Planning Area comprises 2,500 square miles in the southern portion of the Colorado Hydrologic Region, almost all of it in Imperial County. A small portion in the southwestern part of the planning area lies within the San Diego region. The easterly and westerly boundaries are contiguous with the westerly and easterly boundaries of the East Colorado River Basin and the Anza-Borrego Planning Area, respectively. Its northerly boundary is along Salton Sea and the Coachella Valley Planning Area and its southerly boundary follows the international border with Mexico. The Planning Area's central feature is the flat, fertile Imperial Valley. The principal communities are El Centro, Brawley, and Calexico. Surface waters mostly drain toward the Salton Sea. The New and Alamo rivers convey agricultural irrigation drainage water from farmlands in the Imperial Valley, surface runoff, and lesser amounts of treated municipal and industrial waste waters from the Imperial Valley. The flow in the New River also contains agricultural drainage, treated and untreated sewage, and industrial waste discharges from Mexicali, Mexico. Average annual precipitation ranges from less than 3 inches over most of the planning area to about 8 inches in the Coyote Mountains on the western border. Colorado River water, imported via the All American Canal, is the predominant water supply and is used for irrigation, industrial, and domestic purposes.

Groundwater Resources

The San Diego region overlies a complex groundwater resource that varies greatly throughout the region. The region has three general categories of aquifers: fractured rock aquifers, alluvial and sedimentary aquifers, and desert basin aquifers (see Figure 4.10-2 for a map of the groundwater basins). Fractured rock underlies approximately most of the San Diego region. Fractured rock aquifers are present in the foothills and mountainous areas of the region where precipitation is higher than in areas with lower elevations. Fractured rock aquifers typically have much less storage capacity than alluvial or sedimentary



aquifers. Alluvial and sedimentary aquifers underlay a relatively small area of the region. These aquifers are typically found in river and stream valleys, around lagoons, near the coastline, and in the intermountain valleys. Most of these aquifers have relatively high hydraulic conductivity, porosity, and storage and in general would be considered productive aquifers on the basis of their hydrogeologic characteristics. Desert basin aquifers, found in the eastern part of the region, are characterized by extremely limited groundwater recharge, but typically have large storage volumes (County of San Diego 2009). Groundwater in the coastal communities of the San Diego region is relatively shallow as a result of the proximity of the ocean and can be approximated based on the elevation of an area. In general, groundwater is encountered a few feet AMSL in the downtown area. Areas very close to San Diego Bay may see daily changes in groundwater level resulting from tidal variation. Groundwater levels in other areas of San Diego may be locally affected by temporary dewatering systems for adjacent structures under construction. Below-grade structures located within these coastal communities may require temporary dewatering to lower the groundwater table. City ordinances deter permanent dewatering. Below-grade construction farther inland can typically take place without the need for dewatering, depending on the depth of the proposed excavation. Below-grade structures can also be designed to withstand hydrostatic pressures of the permanent groundwater table. Therefore, it is generally feasible to construct multilevel below-grade structures in the San Diego region. Imported water from member agencies of the San Diego County Water Authority (SDCWA) provides most of the potable water needs within the western one-third of the San Diego region, in which about 99 percent of the population is located (refer to Section 4.17 for a more detailed discussion about water supply). The remaining portion of the region (approximately 65 percent by area and 1 percent of the served population) is completely dependent on groundwater resources (County of San Diego 2009). Within the City of San Diego, the geography provides limited natural local supplies in the form of groundwater, and it is not currently considered a usable potable water resource. With the proximity to the ocean and the shallow location of the water table, groundwater and ocean water mix subsurface and become brackish. To become usable, much of the available groundwater would need to undergo desalination (City of San Diego 2007). Surface Water Quality

Untreated storm water can contain a number of pollutants that may eventually flow to surface waters. The primary cause of water pollution is the discharge of inadequately treated storm water runoff into the natural water system. Rapid growth and urbanization have placed increased pressure on water resources and resulted in local impacts to water quality, especially in the western portion of the San Diego region. In general, urbanization increases the amount of pollutants generated by human activities within a watershed, and increases the amount of impervious surfaces, thus reducing the amount of water that would normally infiltrate into the soil and be filtered naturally. Pollutants, such as motor oil, antifreeze, sediment, heavy metals, fertilizers and pesticides, and bacteria and viruses can be transported to surface waters in storm water runoff. The storm water conveyance system is not connected with the sanitary sewer system; therefore, unless adequate best management practices (BMPs) are incorporated, urban runoff can affect surface water and groundwater water quality. Watersheds with Special Pollutant Concerns

Local receiving water conditions may require specialized attention. The three local conditions to consider are as follows:



• Ocean waters designated as an “Area of Special Biological Significance” (ASBS),

• Waters listed as impaired on the CWA Section 303(d) list of water quality limited segments (as described below), and

• Waters with established total maximum daily loads (TMDLs). The SWRCB’s California Ocean Plan identifies 34 locations along the California coast as ASBS locations. The Ocean Plan prohibits the discharge of wastes into these locations, thus barring discharges associated with industrial activities, publicly owned treatment works, and other traditional point discharges (SWRCB 2005). In March 2008, the SWRCB released a draft Special Protections for Selected Storm Water and Nonpoint Source Discharges into ASBSs that defines design criteria for treating storm water discharges and elimination of dry-weather discharges associated with non-storm-water sources. The San Diego region contains two ASBS locations, the La Jolla ASBS and the San Diego-Scripps ASBS, both within the Los Peñasquitos watershed. These locations are adjacent and extend from the northern bluffs of La Jolla through the UC San Diego campus of the Scripps Institute of Oceanography. See Figure 4.10-1 for the location of these ASBSs in the region. Proposed development in the watershed of an ASBS may be prohibited; however, the project proponent needs to contact the municipality for further guidance in contending with ASBS prohibitions. On June 28, 2007, the U.S. Environmental Protection Agency (USEPA) gave final approval for SWRCB’s 2006 CWA Section 303(d) List of Water Quality Limited Segments. To provide an interpretation of current water quality issues in surface waters throughout the San Diego region, Table 4.10-1 summarizes the impaired water segments relative to their HUs in the project region, while Figure 4.10-1 illustrates the geographic location of impaired water body segments in the San Diego region. The RWQCBs have prepared updated lists (i.e., 2008 CWA Section 303(d) List of Water Quality Limited Sections) that are pending approval at the SWRCB.

Table 4.10-1 Common Watersheds and 2006 CWA Section 303(d) Impaired Waters

Water body Pollutant/Stressor Hydrologic Unit SAN DIEGO HYDROLOGIC REGION

Laguna Canyon Channel Sediment Toxicity 90112000 English Canyon Benzo[b]fluoranthene, Dieldrin, Sediment Toxicity 90113000 Oso Creek (at Mission 9 R Viejo Golf Course) Chloride, Sulfates, Total Dissolved Solids 90120000 San Juan Creek DDE, Indicator Bacteria 90120000 Santa Margarita Lagoon Eutrophic 90211000 De Luz Creek Iron, Manganese 90221000 Rainbow Creek Iron, Sulfates, Total Dissolved Solids 90222000

Sandia Creek Iron, Manganese, Nitrogen, Sulfates, Total Dissolved Solids

90222000

Santa Margarita River (Upper) Phosphorus 90222000 Temecula Creek Nitrogen, Phosphorus, Total Dissolved Solids 90251000 Murrieta Creek Iron, Manganese, Nitrogen, Phosphorus 90252000 Long Canyon Creek Total Dissolved Solids 90283000 Guajome Lake Eutrophic 90311000 San Luis Rey River Chloride, Total Dissolved Solids 90311000 Loma Alta Slough Eutrophic, Indicator Bacteria 90410000 Buena Vista Creek Sediment Toxicity 90421000 Buena Vista Lagoon Indicator Bacteria, Nutrients, Sedimentation/Siltation 90421000 Agua Hedionda Lagoon Indicator Bacteria, Sedimentation/Siltation 90431000 Buena Creek DDT, Nitrate and Nitrite, Phosphate 90432000



Water body Pollutant/Stressor Hydrologic Unit Cottonwood Creek (San Marcos Creek watershed)

DDT, Phosphorus, Sediment Toxicity 90451000

Encinitas Creek Phosphorus 90451000 San Marcos Creek DDE, Phosphorus, Sediment Toxicity 90451000 San Marcos Lake Ammonia as Nitrogen, Nutrients, Phosphorus 90452000

Escondido Creek DDT, Manganese, Phosphate, Selenium, Sulfates, Total Dissolved Solids

90461000

San Elijo Lagoon Eutrophic, Indicator Bacteria, Sedimentation/Siltation 90461000 Reidy Canyon Creek Phosphorus 90462000

Green Valley Creek Chloride, Manganese, Pentachlorophenol (PCP), Sulfates

90521000

Hodges, Lake Color, Manganese, Nitrogen, pH, Phosphorus, Turbidity

90521000

Kit Carson Creek Pentachlorophenol, Total Dissolved Solids 90521000 Felicita Creek Aluminum, Total Dissolved Solids 90523000 Cloverdale Creek Phosphorus, Total Dissolved Solids 90532000 Sutherland Reservoir Color, Manganese, pH 90553000 Los Peñasquitos Creek Phosphate, Total Dissolved Solids 90610000 Los Peñasquitos Lagoon Sedimentation/Siltation 90610000 Soledad Canyon Sediment Toxicity 90610000 Mission Bay (area at mouth of Rose Creek only)

Eutrophic, Lead 90630000

Mission Bay (area at mouth of Tecolote Creek only)

Eutrophic, Lead 90630000

Tecolote Creek Cadmium, Copper, Indicator Bacteria, Lead, Phosphorus, Toxicity, Turbidity, Zinc

90650000

Famosa Slough and Channel Eutrophic 90711000 Murray Reservoir pH 90711000

San Diego River (Lower) Fecal Coliform, Low Dissolved Oxygen, Phosphorus, Total Dissolved Solids

90711000

Forester Creek Fecal Coliform, Oxygen-Dissolved, pH, Phosphorus, Total Dissolved Solids

90712000

San Vicente Reservoir Chloride, Color, Manganese, pH (high), Sulfates 90721000 El Capitan Lake Color, Manganese, pH 90731000 Chollas Creek Copper, Indicator Bacteria, Lead, Zinc 90822000 Sweetwater Reservoir Oxygen-Dissolved 90921000 Loveland Reservoir Aluminum, Manganese, Oxygen-Dissolved 90931000 San Diego Bay PCBs (Polychlorinated Biphenyls) 91010000 Poggi Canyon Creek DDT 91020000

Otay Reservoir, Lower Color, Iron, Manganese, Nitrogen - Ammonia (Total Ammonia), pH (high)

91031000

Tijuana River Eutrophic, Indicator Bacteria, Low Dissolved Oxygen, Pesticides, Solids, Synthetic Organics, Trash

91111000

Tijuana River Estuary Eutrophic, Indicator Bacteria, Lead, Low Dissolved Oxygen, Nickel, Pesticides, Thallium, Trash

91111000

Barrett Lake Color, Manganese, pH 91130000 Pine Valley Creek (Upper) Enterococcus, Phosphorus, Turbidity 91141000 Morena Reservoir Color, Manganese, pH 91150000

Pacific Ocean Shoreline (Various Locations) Indicator Bacteria, PCBs (Polychlorinated Biphenyls)

90113000, 90421000, 90114000, 90461000, 91010000, 90112000, 90410000, 90120000, 90130000, 90711000,



Water body Pollutant/Stressor Hydrologic Unit 90511000, 90111000, 90311000, 90451000, 90630000, 91111000

San Diego Bay Shoreline (Various Locations)

Benthic Community Effects, Chlordane, Copper, Lindane/Hexachlorocyclohexane (HCH), Mercury, PAHs (Polycyclic Aromatic Hydrocarbons), PCBs (Polychlorinated Biphenyls), Sediment Toxicity, Zinc

90822000, 90810000, 90911000, 91010000, 90821000, 90822000, 90810000, 90832000, 90831000,

COLORADO RIVER BASIN HYDROLOGIC REGION

Alamo River Chlorpyrifos, DDT, Dieldrin, PCBs, Selenium, Toxaphene

72310000

Coachella Valley Storm Water Channel Pathogens, Toxaphene 71947000 Colorado River (Imperial Reservoir to California-Mexico Border)

Selenium 72700000

Imperial Valley Drains DDT, Deildrin, Endosulfan 72310000

New River

1,2,4-Trimethylbenzene, Chlordane, Chloroform, Chlorpyrifos, Copper, DDT, Diazinon, Dieldrin, Mercury, meta-para xylenes, Nutrients, Organic Enrichment, o-Xylenes, PCBs, p-Cymene, p-Dichlorobenzene, pesticides, Selenium, Toluene, Tozaphene, Toxicity, Trash

72800000

Palo Verde Outfall Drain and Lagoon DDT, Pathogens 71540000 Salton Sea Nutrients, Salinity, Selenium 72800000

Source: SDRWQCB 2006; CRBRWQCB 2006b Placement of a water body onto the 303(d) list requires the RWQCB to make further analysis of the impairment and develop TMDLs for addressing the impairment. Once a TMDL is established, it may impose conditions on development either through an implementation plan and schedule for the listed water, or through special conditions required of the municipality affected by the numeric criteria of the TMDL. At this time, several 303(d) listed water body segments in the San Diego region are at various stages of TMDL development. The SWRCB-approved TMDLs in the San Diego Hydrologic Region are as follows:

• Diazinon and metals for Chollas Creek; • Nitrogen and phosphorus for Rainbow Creek; • Dissolved copper for Shelter Island Yacht Basin, San Diego Bay; • Indicator bacteria for Baby Beach and Shelter Island Shoreline Park Shorelines; and • Indicator bacteria for 20 specific beaches and creeks (Resolution R9-2010-0001).

The following are TMDL amendments that are pending approval in the San Diego region:

• San Diego Bay marine sediments for the mouth of Chollas Creek, 7th Street Channel, and Switzer Creek, B Street/Broadway Piers, Downtown Anchorage, Naval Station Submarine Base;

• TDS for Lower Agua Hedionda Creek;



• Nutrients for Santa Margarita Lagoon, Loma Alta Slough, Buena Vista Lagoon, San Elijo Lagoon, and Famosa Slough and channel;

• Sedimentation for Buena Vista Lagoon, Agua Hedionda Lagoon, San Elijo Lagoon, and Los Peñasquitos Lagoon;

• Bacteria for Loma Alta Slough, Buena Vista Lagoon, Agua Hedionda Lagoon, San Elijo Lagoon, Pacific Ocean Shorelines at Loma Alta, Buena Vista, and Escondido creeks; and

• Tijuana River Estuary for sedimentation and trash. The SWRCB-approved TMDLs in the Colorado Hydrologic Region are as follows:

• Alamo River Sedimentation/Siltation TMDL (Approved on June 28, 2002); • New River Pathogen TMDL (Approved on August 14, 2002); • New River Sedimentation/Siltation TMDL (Approved on March 31, 2003); • New River Trash TMDL (Approved on September 24, 2007); and • Imperial Valley Drains Sedimentation/Siltation TMDL (Approved on September 30, 2005).

The following are TMDL amendments that are pending approval in the Colorado Hydrologic Region:

• Coachella Valley Stormwater Channel Bacterial Indicators TMDL; • New River Dissolved Oxygen TMDL; • New River Volatile Organic Compounds (VOCs) TMDL; • Palo Verde Outfall Drain Bacterial Indicators TMDL; and • Salton Sea Nutrient TMDL.

Flood Hazards and Flood Control

The climate in the San Diego region is semiarid and the seasonal precipitation is highly variable in frequency, magnitude, and location. Infrequent high precipitation amounts can rush down steep canyons and flood areas unexpectedly. Flooding in the San Diego region and the rest of Southern California most frequently occurs during winter storm events between the months of November and April, and occasionally during the summer when a tropical storm makes landfall in the region. Most flooding events occur over several days but can also develop within a matter of hours, particularly in narrow valleys (City of San Diego 2010). However, as the San Diego region averages approximately 10 inches of rainfall annually, flooding is not frequent and usually occurs around the region’s coastal lagoons and estuaries, as well as in the lower reaches of rivers and creeks near the Pacific Ocean. The County Department of Sanitation and Flood Control and public works/engineering departments of incorporated cities in the San Diego region are responsible for designing, constructing, and maintaining flood control facilities in their respective jurisdictions. These responsibilities include the evaluation of proposed construction projects with regard to their potential to increase flood hazard. The basic tools for regulating construction in hazardous floodplain areas are local zoning techniques and Federal Emergency Management Agency (FEMA) floodplain mapping. The Federal Insurance Rate Map (FIRM) is the official map created and distributed by FEMA and the National Flood Insurance Program (NFIP) that delineates the Special Flood Hazard Areas (SFHAs), those areas subject to inundation by the base flood, for every county and community that participates in the NFIP. FIRMs contain flood risk information based on historic, meteorological, hydrologic, and hydraulic data, as well as open-space



conditions, flood control works, and development. Figure 4.10-3 shows FEMA floodway and floodplain areas for the San Diego region. In addition to the FEMA FIRMs, the County of San Diego has developed its own flood maps that account for additional areas of known risk. The County flood maps delineate 1 percent annual chance (100-year) riverine flood boundaries and elevations for areas not studied by FEMA. The County Mapping Program has mapped miles of rivers and streams in the unincorporated area. Proper zoning in floodplains can be beneficial in the preservation of open space, retention of floodplains as groundwater recharge areas, and directing development to areas less prone to flooding. The potential for seiche hazard would correspond to large surface water areas (lakes and ocean shoreline) where earthquakes and high winds could cause abnormal water levels; tsunami hazards would be limited to the lower shoreline elevations along the Pacific coast, San Diego Bay, Mission Bay, and the five coastal lagoons. The California Department of Conservation has maps (CADC 2011) showing the areas of inundation from tsunamis for the San Diego region that can be used to determine inundation potential. Storm Water Drainage and Management

A vast amount of the unincorporated portion of the San Diego region is rural land that does not support or require storm water drainage facilities. In contrast, most urban areas within the incorporated areas of the San Diego region have a range of storm water drainage facilities, which convey surface water runoff to the area’s water bodies and ultimately the Pacific Ocean (City of San Diego 2010). Each jurisdiction within the project area requires the implementation of storm water pollution prevention efforts such that conveyance systems are designed to protect the surface water and groundwater quality as mandated by the state and federal regulations. These regulations require a multifaceted approach that involves infrastructure improvements and maintenance; water quality monitoring; source identification of pollutants; land use planning policies and regulations; and pollution prevention activities such as education, code enforcement, outreach, public advocacy, and training. 4.10.2 REGULATORY SETTING

Numerous laws provide a basis for water quality, drainage, and flooding and establish the goals and objectives that guide the region’s water quality programs. Federal, state, and local government entities are responsible for ensuring compliance with these regulations within the region. Federal Regulations

Clean Water Act

The principal law that serves to protect the nation’s waters is the Federal Water Pollution Control Act, which was originally enacted in 1948. This legislation, more commonly referred to as the Clean Water Act, underwent significant revision when Congress, in response to the public’s growing concern of widespread water pollution, passed the Federal Water Pollution Control Act Amendments of 1972. The 1972 legislation established two fundamental, national goals: eliminate the discharge of pollutants into the nation’s waters and achieve water quality that is both “fishable” and “swimmable.” The 1972 amendments to the CWA also prohibited the discharge of any pollutant to “waters of the U.S.” from any point source (e.g., a discharge pipe) unless the discharge was authorized by a National Pollutant Discharge Elimination System (NPDES) permit. However, non-point source discharges (i.e., storm water or urban runoff) were not fully covered under the NPDES permit program until Congress amended the CWA in 1987.

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Floodplains

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In the 1987 CWA amendments, Congress directed USEPA to establish a permitting framework under the NPDES program to address storm water discharges associated with urban areas and certain industrial activities. USEPA subsequently developed a two-phased NPDES permitting program. Relative to water quality protection and management for the proposed project, several sections of the CWA are important:

• Section 303(d) –TMDLs • Section 401 – Water Quality Certification • Section 402 – NPDES Program • Section 404 – Discharge of Dredge or Fill Material

These sections are further described below: Section 303(d) – Total Maximum Daily Loads

CWA Section 303(d) mandates that states, territories, and authorized tribes develop a list of segments of water that do not meet water quality standards, even after pollution control technology has been implemented for point sources of pollution. The RWQCBs are required to prepare the CWA Section 303(d) List of Water Quality Limited Segments Requiring TMDLs and submit it to the SWRCB, who then submits it to the USEPA for final approval. RWQCBs are required by law to establish TMDLs. These are action plans designed to improve the quality of water resources. As part of the TMDL process, municipalities must examine the water quality problems and identify sources of pollutants in order to create specific actions designed to improve water quality. As of 2008, approximately 96 water segments in the San Diego region are considered impaired (i.e., do not meet water quality standards) and will require a TMDL. The most current approved 303(d) list is from 2006. In 2008, the RWQCB created an update and this has yet to be approved. The water segments in the San Diego region that are listed as impaired are identified in Table 4.10-1. Section 401 – Water Quality Certification

Every applicant for a federal permit or license for any activity that may result in a discharge to a waterbody must obtain State Water Quality Certification for the proposed activity and comply with state water quality standards prescribed in the Certification. In California, these certifications are issued by the SWRCB under the auspices of the RWQCB. Most certifications are issued in connection with U.S. Army Corps of Engineers (USACE) CWA Section 404 permits for dredge and fill discharges (see below). Section 402 – NPDES Program

Section 402 of the CWA establishes the NPDES permit program to regulate the discharge of pollutants from point sources. The CWA defines point sources of water pollutants as “any discernable, confined, and discrete conveyance” that discharges or may discharge pollutants. These are sources from which wastewater is transmitted in some type of conveyance (pipe and channel) to a waterbody, and are classified as municipal or industrial. Municipal point sources consist primarily of domestic treated sewage and processed water, including municipal sewage treatment plant outfalls and storm water conveyance system outfalls. These outfalls contain harmful substances that are emitted directly into waters of the U.S. Without a permit, the discharge of pollutants from point sources into navigable waters of the U.S. is prohibited. NPDES permits require regular water quality monitoring. Amendments to the CWA in 1987 further strengthened regulation of pollutants by establishing a framework for the regulation of storm water and other types of urban runoff. Urban runoff is primarily



caused by non-point source pollutants, which now contribute a larger portion of many kinds of pollutants into our waters. To regulate storm water (non-point source) discharges, USEPA developed the two-phased NPDES permit program described below. In November 1990, under Phase I of its storm water program, USEPA published NPDES permit application requirements for municipal and industrial storm water discharges. These application requirements include the following:

• Municipalities that own and operate separate storm drain systems serving populations of 100,000 or more, or that contribute significant pollutants to waters of the U.S., must obtain a municipal storm water NPDES permit.

• A municipality must develop and implement a storm water management program to obtain a permit.

• The municipal storm water management program must address how to reduce pollutants in industrial storm water discharges and other discharges that are contributing a substantial pollutant load to their systems.

• Facilities that are discharging storm water associated with industrial activity, including construction activities that disturb 5 or more acres, must acquire industrial storm water NPDES permit coverage.

On August 7, 1995, USEPA amended the NPDES permit application requirements in order to focus on Phase II storm water discharges, such as discharges caused by:

• Commercial, light industrial, and institutional activities, • Construction activities under 5 acres, and • Municipal storm drain systems serving populations under 100,000.

Similar to Phase I requirements, the NPDES Phase II permit program also requires the development and implementation of storm water management plans to reduce such discharges and the pollutants that they contain. Implementation of the CWA is the responsibility of USEPA; however, in many states, USEPA has delegated administration of the NPDES permit program to the state water quality control authority. In California, the SWRCB and its RWQCBs administer the NPDES permit program. Currently, discharges from construction, industrial, and municipal activities are regulated under the NPDES program, all of which are described further under the California NPDES Permit Program below. Section 404 – Discharge of Dredge or Fill Material

This section establishes a permit program, administered by USACE, to regulate the discharge of dredge or fill materials into waters of the U.S., including wetlands. Activities in waters of the U.S. that are regulated under this program include fills for development, water resource projects (such as dams and levees), infrastructure development (such as highways and airports), and conversion of wetlands to uplands for farming and forestry. CWA Section 404 permits are issued by USACE. Refer to Section 4.4 for the more information regarding wetlands.



Section 10 of the Rivers and Harbors Act

Section 10 of the Rivers and Harbors Act, administered by USACE, requires permits for all structures (such as riprap) and activities (such as dredging) in navigable waters of the U.S. Executive Order 11990 - Protection of Wetlands

This Executive Order is an overall wetlands policy for all agencies managing federal lands, sponsoring federal projects, or providing federal funds to state or local projects. This Executive Order requires that when a construction project involves wetlands, a finding must be made by the federal agency that there is no practicable alternative to such construction, and that the proposed action includes all practicable measures to minimize impacts to wetlands resulting from such use. Executive Order 11988 - Floodplain Management

Executive Order 11988 directs federal agencies to avoid to the extent practicable and feasible short- and long-term adverse impacts associated with the occupancy and modification of floodplains and to avoid direct and indirect support of floodplain development wherever there is a practicable alternative. Further, this Executive Order requires the prevention of uneconomic, hazardous, or incompatible use of floodplains; protection and preservation of the natural and beneficial floodplain values; and consistency with the standards and criteria of the National Flood Insurance Program (NFIP). Federal Highway Administration regulations require that a local hydraulic study and risk assessment be performed where a planned facility or action would encroach on a base floodplain or support incompatible floodplain development. When the hydraulic study indicates significant encroachment, findings must be made that it is the only practicable alternative. The hydraulic study and risk assessment protocol are set forth in the Caltrans Highway Design Manual (Caltrans 2010). This manual provides guidance and procedures whenever an encroachment permit is anticipated. National Flood Insurance Act

The National Flood Insurance Act of 1968 established the NFIP. The NFIP is a federal program administered by the Flood Insurance Administration of FEMA. It enables individuals who have property (a building or its contents) within the 100-year floodplain to purchase insurance against flood losses. Community participation and eligibility, flood hazard identification, mapping, and floodplain management aspects are administered by state and local programs and support directorate within FEMA. FEMA works with the states and local communities to identify flood hazard areas and publishes a flood hazard boundary map of those areas. Figure 4.10-3 shows FEMA floodway and floodplain areas for the San Diego region. Floodplain mapping is an ongoing process in the county; such maps must be regularly updated for both major rivers and tributaries as land uses and development patterns change. State Regulations

Caltrans NPDES Permit

In 1999, Caltrans was issued a statewide NPDES permit (Order 99-06-DWQ), which requires Caltrans to regulate nonpoint source discharge from its properties, facilities, and activities. The Caltrans permit requires development of a program for communication with local agencies, and coordination with other Municipal Separate Storm Sewer Systems (MS4) storm sewer system programs where those programs overlap geographically with Caltrans facilities. As part of the permit, Caltrans is required to create and



annually update a Stormwater Management Plan (SWMP) that is used to outline the regulation of pollutant discharge caused by current and future construction and maintenance activities. SWMP requirements apply to discharges from Caltrans storm water conveyances, including catch basins and drain inlets, curbs, gutters, ditches, channels, and storm drains. The SWMP applies to discharges consisting of storm water and non-storm water resulting from the following:

• Maintenance and operation of state-owned highways, freeways, and roads; • Maintenance facilities; • Other facilities with activities that have the potential for discharging pollutants; • Permanent discharges from subsurface dewatering; • Temporary dewatering; and • Construction activities

The discharges addressed by the SWMP flow through municipal storm water conveyance systems or flow directly to surface water bodies in the state. These surface water bodies include creeks, rivers, reservoirs, lakes, wetlands, lagoons, estuaries, bays, and the Pacific Ocean and tributaries. This SWMP applies to the oversight of outside agencies’ or non-Caltrans entities’ (third parties) activities performed within Caltrans’ MS4 to ensure compliance with storm water regulations. Non-Caltrans activities include highway construction and road improvement projects, as well as residential use and business operations on leased property. The SWMP must be approved by the SWRCB and, as specified in the permit, it is an enforceable document. Compliance with the permit is measured by implementation of the SWMP. Caltrans’ policies, manuals, and other guidance related to storm water are intended to facilitate implementation of the SWMP. Caltrans also requires all contractors to prepare and implement a program to control water pollution effectively during the construction of all projects (Caltrans 2003). Construction General Permit

The State of California adopted a new Construction General Permit effective on July 1, 2010. SWRCB Water Quality Order 2009-0009-DWQ (Construction General Permit) regulates construction site storm water management. Dischargers whose projects disturb one or more acres of soil, or whose projects disturb less than one acre but are part of a larger common plan of development that in total disturbs one or more acres, are required to obtain coverage under the general permit for discharges of storm water associated with construction activity. This requirement includes linear projects that disturb one or more acres. Construction activity subject to this permit includes clearing, grading, and disturbances to the ground, such as stockpiling or excavation, but does not include regular maintenance activities performed to restore the original line, grade, or capacity of the facility. Permit applicants are required to submit a Notice of Intent (NOI) to the SWRCB and to prepare a Storm Water Pollution Prevention Plan (SWPPP). The SWPPP identifies BMPs that must be implemented to reduce construction effects on receiving water quality based on pollutants. The BMPs identified are directed at implementing both sediment and erosion control measures and other measures to control chemical contaminants. The SWPPP shall also include descriptions of the BMPs to reduce pollutants in storm water discharges after all construction phases have been completed at the site (postconstruction BMPs). The SWPPP should contain a site map(s) that shows the construction site perimeter, existing and proposed buildings, lots, roadways, storm water collection and discharge points, general topography both before and after construction, and drainage patterns across the project. Additionally, the SWPPP must



contain a visual monitoring program, a chemical monitoring program for "nonvisible" pollutants to be implemented if there is a failure of BMPs, and a sediment monitoring plan if the site discharges directly to a waterbody listed on the 303(d) list for sediment. The permit includes several new requirements (as compared to the previous Construction General Permit, 99-08-DWQ), including risk level assessment for construction sites, an active storm water effluent monitoring and reporting program during construction (for risk level II and III sites), rain event action plans for certain higher risk sites, and numeric effluent limitations as well as numeric action levels for pH and turbidity. If a single construction project traverses more than one RWQCB jurisdiction, a complete NOI package (NOI, site map, and fee) and Notice of Termination (upon completion of each section), must be filed for each RWQCB. Porter-Cologne Water Quality Control Act

Under the Porter-Cologne Water Quality Control Act (California Water Code Division 7 Section 13000), the SWRCB is provided with the ultimate authority over state water quality policy. However, Porter-Cologne also established nine RWQCBs to provide oversight on water quality issues at a regional and local level. The RWQCBs are required to prepare and update a Basin Plan for their respective regions. Pursuant to the CWA NPDES program, the RWQCB also issues permits for point source discharges that must meet the water quality objectives and must protect the beneficial uses defined in the Basin Plan. The NPDES permit is described further below in the section discussing local and regional regulations. California Department of Fish and Game Code

Under Sections 1601–1603 of the Fish and Game Code, agencies are required to notify CDFG prior to implementing any project that would divert, obstruct, or change the natural flow or bed, channel, or bank of any river, stream, or lake. CEQA LID Guidance

The Governor’s Office of Planning and Research provides LID guidance standards relating to the CEQA process. The guidance document, released on August 5, 2009, is entitled CEQA and Low Impact Development Stormwater Design: Preserving Stormwater Quality and Stream Integrity Through CEQA Review and provides recommendations on LID-related mitigation measures and benefits. Local and Regional Plans and Policies

San Diego Municipal Storm Water Permit

In January of 2007, under the authority of the CWA amendments and NPDES Permit regulations, the RWQCB renewed Order R9 2007-0001, also referred to as the Municipal Storm Water Permit (first issued on July 16, 1990, and then renewed on February 21, 2001) to the County of San Diego, the 18 incorporated cities of San Diego County, San Diego Unified Port District, and the San Diego County Regional Airport Authority. The Municipal Storm Water Permit requires that each jurisdiction covered under the permit prepare a Jurisdictional Urban Runoff Management Plan (JURMP). Each of these JURMPs includes a component addressing construction activities, development planning, and existing development.



The City and County of San Diego, and other local jurisdictions within San Diego regulate water quality through a variety of ordinances and guidelines, including but not limited to, jurisdictional urban runoff management programs, and storm water standards. In accordance with the provisions of the Municipal Permit, the County of San Diego developed a model Standard Urban Runoff Mitigation Plan (SUSMP) (County of San Diego 2011a) and a SUSMP manual (County of San Diego 2008). The model SUSMP and manual identify mitigation strategies required to protect storm water quality for new development and significant redevelopment within the San Diego region. The County’s model SUSMP outlines a template for municipalities within the San Diego region to follow in preparing their respective SUSMPs. Development within each respective County of San Diego municipality is subject to each respective SUSMP, accordingly. The County’s model SUSMP establishes a series of source control, site design, and treatment control BMPs that are to be implemented by all Priority Development Projects (PDP). PDP include new development, redevelopment projects that create, add, or replace 5,000 square feet, and pollutant generating projects. Refer to the County of San Diego for the specific categories that are defined as PDP. Each jurisdiction within San Diego County (i.e., copermittees of the Municipal Storm Water Permit) has adopted their own SUSMP. A PDP should refer to the SUSMP that has jurisdiction for the project for guidance on the mitigation of storm water pollutants. Each transportation network improvements and land use changes associated with regional growth within the 2050 RTP/SCS would require coordination with appropriate municipal staff to determine if any project or watershed conditions would affect selection and design of BMPs. Adherence with the guidance provided by the County of San Diego Low Impact Development (LID) Handbook (County of San Diego 2007) and compliance with the Stormwater Pollutant Sources/Source Control Checklist included in the County’s Model SUSMP (County of San Diego 2011a) or related municipal SUSMP would reduce potential storm water runoff impacts to levels of insignificance. Hydromodification Management Plan

Provision D.1.g of RWQCB Order R9-2007-0001 requires the San Diego Stormwater Copermittees (the cities within the San Diego region as well as the County government) to implement a Hydromodification Management Plan (HMP) “to manage increases in runoff discharge rates and durations from all PDP, where such increased rates and durations are likely to cause increased erosion of channel beds and banks, sediment pollutant generation, or other impacts to beneficial uses and stream habitat due to increased erosive force.” To address this permit condition, the Copermittees proceeded with developing an HMP that meets the intent of the Order as a part of their SUSMP. The Countywide Model includes the HMP as an appendix. The Order requires the Copermittees to develop an HMP for all PDP, with certain exemptions. The HMP must include standards to control flows within the geomorphically significant flow range. Interim Hydromodification Criteria were prepared and became effective in November 2007. The HMP was prepared in 2009 and was finalized in January 2011 (County of San Diego 2011b). This finalized plan supersedes all previous versions and criteria. The HMP requires PDP to implement hydrologic control measures so that postproject runoff flow rates and durations do not exceed preproject flow rates and durations where they would result in an increased potential for erosion or significant impacts to beneficial uses or violate the channel standard. The project proponent would have to:

(1) Demonstrate that there would be no net increase in impervious area and peak flow rates through incorporation of LID BMPs,



(2) Mitigate flow and duration of runoff by using extended detention basins,

(3) Prepare continuous simulation hydrologic models to compare preproject and mitigated postproject runoff peaks and durations (with hydromodification flow controls), and/or

(4) Show that projected increases in runoff peaks and/or durations would not accelerate erosion by implementing in-stream rehabilitation controls (County of San Diego 2011b).

Additionally, the County developed a LID handbook for guidance in the BMP selection process (County of San Diego 2007). Design techniques include minimizing impervious areas, conserving natural areas, and utilizing vegetation and landscaping for water quality treatment benefits. Construction Dewatering Permits

Construction dewatering discharges must be permitted either by the San Diego RWQCB under the general NPDES Permit CAG919002 (Order R9-2008-0002) for construction dewatering discharge to surface waters or authorized to discharge to local publicly owned treatment works (i.e., industrial or sanitary sewer system of municipal wastewater treatment plants). Discharge via either of these mechanisms must meet applicable water quality objectives, constituent limitations, and pretreatment requirements. San Diego Regional Water Quality Control Board Basin Plan

The Basin Plan for the San Diego Basin, most recently amended in 2007, sets forth water quality objectives for constituents that could have a significant impact related to the beneficial uses of water. Specifically, the Basin Plan is designed to accomplish the following:

(1) Designate beneficial uses for surface water and groundwater,

(2) Set the narrative and numerical water quality objectives that must be attained or maintained to protect the designated beneficial uses and conform to California’s antidegradation policy,

(3) Describe implementation programs to protect the beneficial uses of all water in the region, and

(4) Describe surveillance and monitoring activities to evaluate the effectiveness of the Basin Plan. As discussed in the previous section regarding federal regulations, 303(d) listed water body segments are impaired for specific pollutants. These impairments are dependent upon the beneficial uses of the water body. When beneficial uses, as defined in the Basin Plan, of a water body are impaired by a particular pollutant, the water body would be a candidate for 303(d) listing and the establishment of a TMDL. The type of beneficial use would also influence the TMDL level. Projects implemented within this basin must be designed to protect the beneficial uses of the surrounding water bodies. In addition, the Basin Plan incorporates by reference all applicable SWRCB and RWQCB plans and policies. Flood Control

The County Department of Sanitation and Flood Control and the engineering departments of the incorporated areas are responsible for designing, constructing, and maintaining flood control facilities in their respective jurisdictions. These responsibilities include the evaluation of proposed construction projects with regard to their potential to increase flood hazard. In addition, the requirements for proper runoff management and protection against hydromodification noted above (as well as local codes/ordinances) that are mandated by local municipalities also serve to protect against flood damage at the jurisdictional level.



4.10.3 SIGNIFICANCE CRITERIA

The 2050 RTP/SCS would have a significant impact related to hydrology and water quality if implementation were to:

WQ-1 Violate any water quality standards or waste discharge requirements.

WQ-2 Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, in a manner that would:

• Result in substantial erosion or siltation on- or off-site,

• Substantially increase the rate or amount of surface runoff in a manner that would result in flooding on- or off-site,

• Create or contribute runoff water that would exceed the capacity of existing or planned storm water drainage systems,

• Provide substantial additional sources of polluted runoff, or

• Otherwise substantially degrade water quality.

WQ-3 Place within a 100-year flood hazard area structures that would impede or redirect flood flows.

WQ-4 Expose people or structures to a significant risk of loss, injury, or death involving flooding, including flooding as a result of the failure of a levee or dam.

WQ-5 Expose people or structures to a significant risk of inundation by seiche, tsunami, or mudflow.

4.10.4 IMPACT ANALYSIS

This section analyzes the impacts associated with the implementation of the 2050 RTP/SCS. It is organized in sections to address the two main components of the 2050 RTP/SCS: (1) land use changes associated with regional growth and (2) transportation system improvements. Analysis for each significance criterion includes a program-level discussion of anticipated impacts in the planning horizon years of 2020, 2035, and 2050. Significant impacts are identified and mitigation measures are provided where appropriate. WQ-1 WATER QUALITY STANDARDS OR WASTE DISCHARGE

REQUIREMENTS

As discussed in Section 4.10.2, the CWA established the NPDES framework for regulating discharges of pollutants into the nation’s waters by requiring permits for point-source and nonpoint-source (storm water) discharges into “waters of the United States.” An NPDES permit is required for discharges from all priority development projects, as defined by the RWQCB. In addition, Section 303(d) of the CWA specifies impaired water bodies that are particularly sensitive to pollution. These impaired waters either



have, or will have, TMDLs that serve to regulate the pollutant loads from point sources, nonpoint sources, and natural background conditions. The San Diego region is situated within the jurisdiction of the SDRWQCB and the CRBRWQCB, which implements water quality protection standards through the issuance of various permits for waste discharges. For PDPs involving over 1 acre of disturbed area, the RWQCB would require coverage under the Construction General Permit, preparation of a SWPPP, hydromodification analysis, and sustainable project features—all of which would collectively serve to protect water quality during the construction phase and maintain predevelopment runoff volumes once construction is completed. The Basin Plans prepared by respective RWQCBs prescribe water quality objectives and designates beneficial uses for the various water bodies in the basin. An impact would be considered significant if water quality objectives were violated or permit limitations were exceeded for surface waters and groundwater within these regional basin plans. 2020

Regional Growth/Land Use

By 2020, population within the region is forecasted to increase by 310,568 people; housing by 113,062 units; and employment by 118,535 jobs. New development caused by regional growth would be in the form of new homes, services, commercial areas, industrial centers, schools, and civic uses. Development of these uses would change the views throughout the region, both in beneficial and adverse ways. When comparing existing land use as shown in Figure 4.11-1 and 2020 land use as shown in Figure 4.11-3, no substantial differences occur in the land use patterns, types, or areas of development. The 2050 RTP/SCS would not likely result in major development in areas that are currently completely undeveloped. Some locations that would experience the most extensive land use change and development by 2020 would include areas such as eastern Chula Vista along the SR 125 and I-805 corridors; San Diego community planning areas of San Ysidro and Otay Mesa along the SR 905 corridor; City of San Diego coastal and bay communities south of I-8, including Ocean Beach and the Peninsula planning areas; portions of northern Santee; areas north and south of the SR 56 corridor in the San Diego planning areas of Carmel Valley, Del Mar Mesa, Pacific Highlands Ranch, and Torrey Highlands; the San Marcos area near both the SR 78 and I-15 corridors; and within unincorporated County communities such as Fallbrook, Pala-Pauma Valley, and Valley Center along the I-15 and SR 76 corridors. These anticipated land use changes by 2020 span the western part of the San Diego region and cross many of the county’s watersheds, which would involve particular attention to the following impaired water body concerns: Pogi Canyon Creek and the Tijuana River (southwestern county development), Famosa Slough and the San Diego Bay (Ocean Beach and Point Loma development), San Diego River (northern Santee development), Los Peñasquitos Lagoon (SR-56 corridor development), Agua Hedionda Lagoon (San Marcos development), and Santa Margarita River and San Luis Rey River (Fallbrook development). The development associated with this regional growth and land use changes could impact surface and groundwater quality through the creation of new impervious surfaces. Increased impervious surfaces associated with regional growth and land use changes would collect pollutants that would be transported via storm water to the local municipal storm water conveyance system. Most development by 2020 would be in existing urban areas where the increase in impervious surface would not be substantial. However, rural or semirural areas that would experience an increase in urbanization would also be expected to have an increase in storm water and urban runoff if proper BMPs were not implemented. In undeveloped areas or those with low-density urbanization, potential generation and transport of pollutants to surface waters and groundwater would be expected, and such areas may also be associated with natural or soft-bottom



streams and drainages that may be sensitive water resources (e.g., impaired waters). Typical pollutants associated with increased urbanization would be expected to principally include sediment, oil and grease, metals, and nutrients. As proposed projects are submitted for environmental and engineering review, compliance with applicable regional, state, and federal water quality regulations would appropriately guide project designs such that potential impacts associated with increased runoff and pollutant generation from development and redevelopment are addressed. Improvements associated with the 2050 RTP/SCS would need to be compliant with regulatory requirements that serve to minimize potential surface water quality and groundwater impacts, such as:

• Construction General Permit (Order 2009-0009-DWQ), and/or

• San Diego County Municipal Storm Water Permit (Order R9-2007-0001) and associated requirements of various municipal storm water management plans and land development requirements (e.g., JURMP and SUSMP requirements).

Conformance and compliance to these water quality standards, waste discharge requirements (WDRs), and storm water management programs for priority development projects (PDPs) would require that preproject hydrology be maintained after construction is completed and that associated runoff be treated to remove or reduce pollutants (i.e., impacts to surface water and groundwater quality) to insignificant levels. For projects that discharge to impaired water bodies such as those discussed above, BMPs would be required that target the removal of the pollutants causing the impairment of the water body. The development associated with the increases in population, housing, and employment would also be expected to increase potable water demands for surface and groundwater resources. The impacts to potable water supplies as a result of the increase in water demand are addressed in Section 4.17, Water Supply. SDCWA is required to ensure an appropriate level of reliability to the water supply and, in that effort, prepares the Urban Water Management Plan every 5 years that identifies the future sources of potable water. Further, because the region has a low reliance (approximately 1 percent by population) on groundwater resources as a potable water source, and SDCWA is monitoring groundwater capacity, the regional aquifer reserves would not be significantly impacted. In addition, even though impervious surface increases may occur, current water quality and storm water regulations promote the reduction of impervious surface and the optimization of storm water infiltration (i.e., potential groundwater recharge) opportunities. As referenced in the regulatory setting (Section 4.10.2), the LID designs and various BMPs required of these regulations would serve to attenuate increases in storm water flows, promote infiltration and groundwater recharge, and offset hydromodification impacts. Based on the above analysis and compliance with the regulatory requirements outlined above, growth/land use changes associated with the 2050 RTP/SCS would not violate water quality standards or WDRs, and this impact would be less than significant. Transportation Network Improvements

By 2020, numerous highway, transit, and active transportation (bicycle and pedestrian) improvements, along with other infrastructure projects, are planned for the region in accordance with the 2050 RTP/SCS. The transportation network improvements that would be implemented between 2010 and 2020 generally include widening and/or installation of HOV lanes, and Managed Lanes, and Transit Lanes along portions of I-5, I-15, I-805, SR 78, and SR 94; completion of SR 905 and SR 11; and HOV connector projects along I-805 and SR 78 at I-15. Some key transit network improvements in place by 2020 would include



increases in existing COASTER service, including extension of COASTER service to the San Diego Convention Center and Petco Park. BRT downtown express services from inland and south bay locations would be expanded as well as new BRT routes from the south bay area and along I-15. Rapid bus service would add new routes and streetcar routes would be established. Airport express routes would also be developed. Local bus service would be improved to 15 minutes in key corridors. Double-tracking of the LOSSAN rail corridor would occur to accommodate increased frequency in COASTER and other rail services that utilize this rail line. In addition, the new Mid-Coast Trolley line from Old Town to University Town Center would be constructed and the Green Trolley line would be extended to downtown San Diego. Table 4.10-2 summarizes the transportation improvements for 2020 and the associated 303(d) listed water bodies that they cross. Although many of the impairments in Table 4.10-2 are pesticides that have long been banned from use in the United States, there are sensitive receiving waters along the transportation corridors that would need focused environmental protection relative to construction and operational runoff. Storm water runoff from the proposed transportation improvements may include pollutants (e.g., motor oil, antifreeze, sediment, heavy metals, and landscape fertilizers and pesticides) that could be transported to surface waters if proper BMPs are not incorporated. For transportation improvements that cross sensitive water resources, such as those outlined in Table 4.10-2, the potential for pollutant releases would be greatest during construction (particularly those listed for sediment/siltation). However, the need and design of BMPs would be dictated by the resident soil characteristics, the proposed roadway improvements, the quality of the SWPPP and the integrity of its implementation, and the presence of surrounding sensitive resources. During the SWPPP development process, BMPs would be selected that target the pollutant(s) of concern relative to adjacent impaired water bodies; operation-phase BMPs would be evaluated during the development of drainage designs. As discussed in the Regional Growth section, specific regulations, such as the statewide Construction General Permit, apply to construction and postconstruction impacts; in addition, the Caltrans Statewide Stormwater Program and Management Plan would apply to Caltrans facilities. Where construction is below the local water table, dewatering may be necessary. Although permanent groundwater dewatering is discouraged by the SDRWQCB, it can be permitted via general NPDES Permit CAG919002 (Order R9-2008-0002). Under a temporary or permanent scenario, impacts to surface waters or groundwater quality would be minimized by complying with SDRWQCB permit stipulations. As noted earlier, options are available for discharge to publicly owned treatment works (depending on local capacity issues), which would avoid impacts to surface waters and groundwater. Under either permitting option, there would be no significant impacts to surface or groundwater quality pending compliance with permit conditions. Based on the above analysis and compliance with the regulatory requirements outlined, the 2050 RTP/SCS transportation network improvements would not violate water quality standards or WDRs, and this impact would be less than significant. Conclusion

For 2020, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not violate water quality standards or WDRs, and this impact would be less than significant.



Table 4.10-2 Transportation Improvements by 2020 That Cross 303(d) Listed Water Bodies

Horizon Year Improvement Type Freeway Improvement Impaired Water Body Hydrologic

Unit # Pollutant 2020 Arterials Bear Valley/East Valley/Valley Center - Citrus

Avenue to Beven Drive Escondido Creek 90462000 DDT

2020 Arterials Citracado Parkway II - West Valley to Harmony Grove

Escondido Creek 90462000 DDT

2020 Arterials College Boulevard Bridge - San Luis Rey River San Luis Rey River 90311000 Chloride 2020 Arterials Discovery Street Improvements - McMahr Rd to

Bent Ave/Craven Rd San Marcos Creek 90451000 DDE

2020 Arterials Discovery Street Improvements - McMahr Rd to Bent Ave/Craven Rd

San Marcos Creek 90451000 DDE

2020 Arterials El Camino Real - La Costa Avenue to Arenal Road San Marcos Creek 90451000 DDE 2020 Arterials El Camino Real - La Costa Avenue to Arenal Road San Marcos Creek 90451000 DDE 2020 Arterials El Camino Real - La Costa Avenue to Arenal Road San Marcos Creek 90451000 DDE 2020 Arterials El Camino Real and Cannon Road Agua Hedionda Creek 90431000 Manganese 2020 Arterials South Santa Fe Avenue South - South of Woodland

Drive to Smilax Road Buena Creek 90432000 DDT

2020 Arterials Street Improvements: Discovery Street - Craven Road to West of Twin Oaks Valley Road




2020 Arterials Via Vera Cruz Bridge and Street Improvements - San Marcos Boulevard to Discovery Street


2020 Highways - 2020 I-15 Centre City Parkway to SR 78 Escondido Creek 90462000 DDT 2020 Highways - 2020 I-15 I-8 to SR 163 San Diego River (Lower) 90711000 Fecal Coliform 2020 Highways - 2020 I-15 SR 163 to SR 56 Los Peñasquitos Creek 90610000 Phosphate 2020 Highways - 2020 I-5 Manchester Ave to SR 78 Buena Vista Creek 90421000 Sediment Toxicity 2020 Highways - 2020 I-5 Manchester Ave to SR 78 San Marcos Creek 90451000 DDE 2020 Highways - 2020 SR 76 Melrose Drive to I-15 San Luis Rey River 90311000 Chloride 2020 Highways - 2020 SR 78 I-5 to I-15 Buena Vista Creek 90421000 Sediment Toxicity 2020 Highways - 2020 SR 78 I-5 to I-15 Buena Vista Creek 90421000 Sediment Toxicity 2020 Highways - 2020 SR 78 I-5 to I-15 San Marcos Creek 90451000 DDE 2020 Highways - 2020 SR 78 I-5 to I-15 Buena Creek 90432000 DDT 2020 Transit LOSSAN 2008 Tecolote Creek 90650000 Cadmium 2020 Transit LOSSAN 2008 San Luis Rey River 90311000 Chloride 2020 Transit LOSSAN 2008 San Diego River (Lower) 90711000 Fecal Coliform 2020 Transit LOSSAN 2008 Buena Vista Creek 90421000 Sediment Toxicity 2020 Transit LOSSAN 2008 Los Peñasquitos Creek 90610000 Phosphate 2020 Transit LOSSAN 2008 San Marcos Creek 90451000 DDE 2020 Transit LOSSAN 2008 Soledad Canyon 90610000 Sediment Toxicity




Unit # Pollutant 2020 Transit LOSSAN 2020 San Luis Rey River 90311000 Chloride 2020 Transit LOSSAN 2020 Buena Vista Creek 90421000 Sediment Toxicity 2020 Transit LOSSAN 2020 Los Peñasquitos Creek 90610000 Phosphate 2020 Transit LOSSAN 2020 Tecolote Creek 90650000 Cadmium 2020 Transit LOSSAN 2020 San Luis Rey River 90311000 Chloride 2020 Transit LOSSAN 2020 San Diego River (Lower) 90711000 Fecal Coliform 2020 Transit LOSSAN 2020 Buena Vista Creek 90421000 Sediment Toxicity 2020 Transit LOSSAN 2020 Los Peñasquitos Creek 90610000 Phosphate 2020 Transit LOSSAN 2020 San Marcos Creek 90451000 DDE 2020 Transit LOSSAN 2020 Soledad Canyon 90610000 Sediment Toxicity 2020 Transit LRT Extensions Tecolote Creek 90650000 Cadmium 2020 Transit LRT Extensions San Diego River (Lower) 90711000 Fecal Coliform 2020 Transit SPRINTER 2010 Escondido Creek 90462000 DDT 2020 Transit SPRINTER 2010 Buena Vista Creek 90421000 Sediment Toxicity 2020 Transit SPRINTER 2010 San Marcos Creek 90451000 DDE 2020 Transit SPRINTER 2010 Buena Creek 90432000 DDT 2020 Transit LOSSAN 2008 Tecolote Creek 90650000 Cadmium 2020 Transit LOSSAN 2008 San Luis Rey River 90311000 Chloride 2020 Transit LOSSAN 2008 San Diego River (Lower) 90711000 Fecal Coliform 2020 Transit LOSSAN 2008 Buena Vista Creek 90421000 Sediment Toxicity 2020 Transit LOSSAN 2008 Los Peñasquitos Creek 90610000 Phosphate 2020 Transit LOSSAN 2008 San Marcos Creek 90451000 DDE 2020 Transit LOSSAN 2008 Soledad Canyon 90610000 Sediment Toxicity 2020 Transit SPRINTER 2010 Escondido Creek 90462000 DDT 2020 Transit SPRINTER 2010 Buena Vista Creek 90421000 Sediment Toxicity 2020 Transit SPRINTER 2010 San Marcos Creek 90451000 DDE 2020 Transit SPRINTER 2010 Buena Creek 90432000 DDT 2020 Highways - 2020 SR 76 Melrose Drive to I-15 San Luis Rey River 90311000 Chloride 2020 Highways - 2020 I-15 Centre City Parkway to SR 78 Escondido Creek 90462000 DDT 2020 Highways - 2020 I-15 SR 163 to SR 56 Los Peñasquitos Creek 90610000 Phosphate 2020 Highways - 2020 I-5 Manchester Ave to SR 78 Buena Vista Creek 90421000 Sediment Toxicity 2020 Highways - 2020 I-5 Manchester Ave to SR 78 San Marcos Creek 90451000 DDE 2020 Highways - 2020 SR 78 I-5 to I-15 Buena Vista Creek 90421000 Sediment Toxicity 2020 Highways - 2020 SR 78 I-5 to I-15 Buena Vista Creek 90421000 Sediment Toxicity 2020 Highways - 2020 SR 78 I-5 to I-15 San Marcos Creek 90451000 DDE 2020 Highways - 2020 I-15 I-8 to SR 163 San Diego River (Lower) 90711000 Fecal Coliform 2020 Highways - 2020 SR 78 I-5 to I-15 Buena Creek 90432000 DDT 2020 Arterials El Camino Real and Cannon Road Agua Hedionda Creek 90431000 Manganese 2020 Arterials College Boulevard Bridge - San Luis Rey River San Luis Rey River 90311000 Chloride 2020 Arterials Bear Valley/East Valley/Valley Center - Citrus Escondido Creek 90462000 DDT




Unit # Pollutant Avenue to Beven Drive

2020 Arterials Citracado Parkway II - West Valley to Harmony Grove

Escondido Creek 90462000 DDT







2020 Arterials El Camino Real - La Costa Avenue to Arenal Road San Marcos Creek 90451000 DDE 2020 Arterials El Camino Real - La Costa Avenue to Arenal Road San Marcos Creek 90451000 DDE 2020 Arterials El Camino Real - La Costa Avenue to Arenal Road San Marcos Creek 90451000 DDE 2020 Arterials South Santa Fe Avenue South - South of Woodland

Drive to Smilax Road Buena Creek 90432000 DDT





2020 Transit LOSSAN 2020 San Luis Rey River 90311000 Chloride 2020 Transit LOSSAN 2020 Buena Vista Creek 90421000 Sediment Toxicity 2020 Transit LOSSAN 2020 Los Peñasquitos Creek 90610000 Phosphate 2020 Transit LOSSAN 2020 Tecolote Creek 90650000 Cadmium 2020 Transit LOSSAN 2020 San Luis Rey River 90311000 Chloride 2020 Transit LOSSAN 2020 San Diego River (Lower) 90711000 Fecal Coliform 2020 Transit LOSSAN 2020 Buena Vista Creek 90421000 Sediment Toxicity 2020 Transit LOSSAN 2020 Los Peñasquitos Creek 90610000 Phosphate 2020 Transit LOSSAN 2020 San Marcos Creek 90451000 DDE 2020 Transit LOSSAN 2020 Soledad Canyon 90610000 Sediment Toxicity 2020 Transit LRT Extensions Tecolote Creek 90650000 Cadmium 2020 Transit LRT Extensions San Diego River (Lower) 90711000 Fecal Coliform



2035


By 2035, the population of the region is expected to increase by 801,699 people; housing by 268,094 units; and employment by 312,292 jobs over existing 2010 conditions. As shown in Figure 4.11-4, regional land use and development changes are evident by 2035. Some locations that would experience the most extensive land use change and development by 2035 would include continued growth in eastern Chula Vista along the SR 125 and I-805 corridors; San Diego community planning areas of San Ysidro and Otay Mesa along the SR 905 and SR 125 corridors: northeast of the SR 94 corridor in the unincorporated County planning areas of Jamul/Dulzura, Tecate, and Potrero; eastern Poway along the SR 67 corridor; the County planning area of Ramona along the SR 67 and SR 78 corridors; the County planning areas of Lakeside and Alpine and the Crest, Granite Hills, Dehesa, Harbison Canyon subregion; and multiple north County planning areas along the 1-15 and SR 76 corridors such as Rainbow, Fallbrook, Bonsall, Pala-Pauma Valley, Valley Center, and Hidden Valley. The increased density can be seen when comparing the existing housing density to the 2035 housing density, as shown in Figures 4.13-2 and 4.13-8, respectively. Areas of increased residential density by 2035 would be apparent in some coastal cities such as Oceanside and Encinitas, and City of San Diego coastal communities. Also, increased density would occur in more inland areas along the I-8 corridor through Mission Valley, College Area, and into the City of La Mesa, as well as eastern Chula Vista along the SR 125 corridor. In the northern portion of the region, land use changes to accommodate growth in 2035 in the form of spaced rural residential development would occur along the I-15 corridor north of Escondido toward the northern county line and in more eastern areas along I-8, SR 67, SR 78, and SR 94. The SR 78 corridor, from Escondido to I-5, would experience growth and resulting land use density increases of both residential and commercial/office. As shown in Figure 4.11-4, single-family residential development would increase substantially along this corridor as well as additional commercial and industrial growth. The majority of this growth would be centered around the cities of Vista, San Marcos, and Escondido. The pattern of more dense growth along this segment of the SR 78 corridor is also apparent when comparing the existing housing density to 2035 housing density (see Figures 4.13.2 and 4.13-8 in Section 4.13, Population and Housing) and existing employment density to 2035 employment density (see Figures 4.13-3 and 4.13-9). By 2035, some regional growth would be accommodated in the more eastern, rural areas of the region. Development in these areas would be centered mostly along highway corridors, such as SR 78, SR 67, I-8 east of El Cajon, and SR 94, and generally within San Diego County community planning areas. The unincorporated portions of San Diego County are currently undergoing population growth and expansion of residential land use as indicated by a population increase of 14 percent from 2000 to 2010 as shown in Table 4.11-2. When comparing the existing land uses and 2035 land uses in Figures 4.11-1 and 4.11-4, the 2035 land use pattern would generally involve additional residential development in areas that were previously undeveloped open space or at some time in agricultural use (as discussed in Section 4.2). As discussed in the 2020 analysis, increased impervious surfaces associated with regional growth and land use changes would collect pollutants that would be transported via storm water to the local municipal storm water conveyance system. Typical pollutants associated with increased urbanization would be expected to principally include sediment, oil and grease, metals, and nutrients. These pollutants would impact receiving water bodies without the proper BMPs. Adequate and appropriate BMPs are required by the various regulations described in the 2020 analysis above and in the Regulatory Section (Section 4.10.2). With the development occurring throughout the San Diego region, many of the impaired waters



would be in the vicinity (and would be possible discharge points) for the proposed projects. In these circumstances, applicable regulations, mandated planning/design requirements, and proper implementation of BMPs would protect impaired waters from project-related pollutants. Also discussed in the 2020 analysis, the regional growth and land use changes associated with the 2050 RTP/SCS would also be expected to increase potable water demands for surface and groundwater resources. However, the LID designs and various BMPs required by the regulations would serve to attenuate increases in storm water flows, promote infiltration and groundwater recharge, and offset hydromodification impacts. Transportation Network Improvements

Some key highway improvements in place by 2035 would include continued widening along portions of I-5; additional HOV and Managed Lanes along portions of I-5, I-15, I-805, and SR 52; widening of portions of SR 125 and SR 67; and additional freeway and HOV connector improvements. Some important transit projects operational by 2035 would include continued increases in COASTER service, increases in SPRINTER service, increases in downtown area streetcar service, and substantial increases in rapid bus service throughout the region. The Trolley Blue Line would be extended from UTC to Mira Mesa via Sorrento Mesa and Carroll Canyon; the Orange Line would be extended to Lindbergh Field; Phase 1 of the new Mid-City to Downtown San Diego line would provide service from the Mid-City transit station via El Cajon Boulevard to Downtown; and a new line from Pacific Beach to El Cajon via Kearny Mesa, Mission Valley, and San Diego State University would be established. Double-tracking along the SPRINTER rail line through the cities of Oceanside, Vista, San Marco, and Escondido would take place by 2035 as well as continued double-tracking along the LOSSAN corridor. Table 4.10-3 shows the transportation improvements planned for 2035 that cross 303(d) listed water bodies and the impairments of these waters. As discussed in the 2020 analysis, specific regulations apply to construction and the postconstruction developed condition. Compliance with the water quality regulations described earlier would reduce the associated potential impacts to surface water or groundwater quality to less than significant as each project is designed, analyzed, and permitted for construction. Conclusion

For 2035, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not violate water quality standards or WDRs, and potential impacts to surface and groundwater quality would be less than significant. 2050


By 2050, the population of the region is forecast to increase by 1,160,435 people; housing by 379,664 units; and employment by 501,958 jobs over existing conditions. As shown in Figure 4.11-5, new growth and land use changes in 2050 per the 2050 RTP/SCS are apparent throughout the region. Areas of substantial land use change and development, beyond that described in 2035 would include significant industrial development in the County’s Otay planning area and San Diego Otay Mesa community surrounding the East Otay Mesa POE; throughout County planning areas located along the international border including Tecate, Potrero, Campo/Lake Morena, Boulevard, and Jacumba; throughout the Ramona and Julian planning areas in the unincorporated County; throughout other northeastern County planning





Unit # Pollutant

2035 Highways - 2035 I-5 Manchester Ave to Palomar Airport Rd San Marcos Creek 90451000 DDE


2035 Highways - 2035 I-5 SR 78 to Vandegrift San Luis Rey River 90311000 Chloride

2035 Highways - 2035 I-5 SR 78 to Vandegrift Buena Vista Creek 90421000 Sediment Toxicity


2035 Highways - 2035 I-805 SR 905 to Palomar St Pogi Canyon Creek 91020000 DDT



2035 Transit LOSSAN 2030 San Diego River (Lower) 90711000 Fecal Coliform

2035 Transit LOSSAN 2030 San Marcos Creek 90451000 DDE

2035 Transit LOSSAN 2030 San Luis Rey River 90311000 Chloride

2035 Transit LOSSAN 2030 Buena Vista Creek 90421000 Sediment Toxicity

2035 Transit LOSSAN 2030 Los Peñasquitos Creek 90610000 Phosphate

2035 Transit LOSSAN 2030 Tecolote Creek 90650000 Cadmium






2035 Transit LOSSAN 2030 Soledad Canyon 90610000 Sediment Toxicity

2035 Transit SPRINTER 2035 Escondido Creek 90462000 DDT

2035 Transit SPRINTER 2035 Buena Creek 90432000 DDT


2035 Transit SPRINTER 2035 Buena Vista Creek 90421000 Sediment Toxicity

2035 Transit SPRINTER 2035 San Marcos Creek 90451000 DDE










Unit # Pollutant












2035 Transit LOSSAN 2030 Soledad Canyon 90610000 Sediment Toxicity

2035 Highways - 2035 I-5 SR 78 to Vandegrift San Luis Rey River 90311000 Chloride






2035 Transit SPRINTER 2035 Buena Vista Creek 90421000 Sediment Toxicity

2035 Transit SPRINTER 2035 San Marcos Creek 90451000 DDE




areas, including North Mountain, Desert, and Borrego Springs; and continued development throughout County planning areas located north and east of Escondido extending to the northern border with Riverside County, including Rainbow, Fallbrook, Bonsall, Pala-Pauma Valley, Valley Center, Hidden Valley, Twin Oaks Valley, and North County Metro. Increased population density from 2010 through 2050 can be seen when comparing Figures 4.13-1, and 4.13-10, respectively. Increased density is most apparent in City of San Diego communities near the downtown area near I-5 and I-805 and along the I-8 corridor to the east. Urban centers in the western third of the San Diego region would have most available land developed with single- and multi-family uses, commercial and office uses, and industrial uses. Consistent with the goals of the 2050 RTP/SCS, the dense growth within existing urban centers with high accessibility to transit options allows for the creation of communities that are more sustainable, walkable, transit-oriented, and compact. Substantial dense growth within the urban centers corresponds with major transportation corridors such as I-5, I-8, I-15, and I-805 and these are also alignments that would have extensive transit opportunities. Similar to the description in the 2035 analysis, growth would continue in more eastern locations of the region, such as east of I-15 in the northern area, east of SR 67 through the middle portion of the region, and east of SR 94 in the southern area. However, by 2050, spaced rural residential development would have expanded beyond areas along existing transportation corridors and established rural communities and into areas with very minimal development at present. As shown in Figure 4.11-5, some of these areas include northeast of Escondido to SR 76, areas east of Camp Pendleton, and areas north and south of the SR 78 corridor. As shown in Figure 4.11-5, by 2050, a substantial pocket of industrial development would be located along the planned SR 905 corridor in conjunction with the new Otay Mesa East POE at the international border with Mexico. This is a newly developing area that is planned for mainly industrial use and is highly dependent upon the planned construction of SR 11, SR 905, and the Otay Mesa East POE. With this forecasted development occurring throughout the San Diego region, many of the impaired waters identified (Table 4.10-4) would coincide with the proposed transportation improvements and possibly become ultimate discharge points for project-related runoff. In these circumstances, applicable regulations, mandated planning/design requirements, and proper implementation of BMPs would protect impaired waters from project-related pollutants. As discussed in the 2020 analysis, proposed projects would be submitted for environmental and engineering review, and compliance with applicable regional, state, and federal water quality regulations would appropriately guide project designs such that potential impacts associated with increased runoff and pollutant generation from development and redevelopment are addressed. Improvements associated with the 2050 RTP/SCS would need to be compliant with regulatory requirements that serve to minimize potential surface water quality and groundwater impacts. Based on the above analysis and compliance with the regulatory requirements outlined, the 2050 RTP/SCS growth/land use changes described above and in Section 4.10.2 would not violate water quality standards or WDRs, and this impact would be less than significant. Transportation Network Improvements

Transportation improvements planned for 2050 are located throughout the western half of the San Diego region, but unlike the improvements planned by 2020 and 2035, several of these planned improvements




Horizon Year Improvement Type Freeway Improvement Impaired Water Body Hydrologic Unit # Pollutant

2050 Highways - 2050 I-15 SR 78 to Riverside County Rainbow Creek 90222000 Iron

2050 Highways - 2050 I-15 I-5 to SR 94 Chollas Creek 90822000 Copper

2050 Highways - 2050 I-5 I-8 to La Jolla Village Dr Tecolote Creek 90650000 Cadmium

2050 Highways - 2050 I-5 SR 54 to I-15 Chollas Creek 90822000 Copper

2050 Highways - 2050 I-5 SR 54 to I-15 Chollas Creek 90822000 Copper

2050 Highways - 2050 I-805 Mission Valley Viaduct San Diego River (Lower) 90711000 Fecal Coliform

2050 Highways - 2050 SR 125 SR 905 to San Miguel Rd Pogi Canyon Creek 91020000 DDT

2050 Highways - 2050 SR 52 I-15 to SR 125 Forester Creek 90712000 Fecal Coliform

2050 Highways - 2050 SR 52 I-15 to SR 125 San Diego River (Lower) 90711000 Fecal Coliform








2050 Transit LOSSAN 2050 San Diego River (Lower) 90711000 Fecal Coliform 2050 Highways - 2050 SR 52 I-15 to SR 125 Forester Creek 90712000 Fecal Coliform2050 Highways - 2050 SR 52 I-15 to SR 125 San Diego River (Lower) 90711000 Fecal Coliform2050 Highways - 2050 I-805 Mission Valley Viaduct San Diego River (Lower) 90711000 Fecal Coliform

2050 Highways - 2050 I-15 SR 78 to Riverside County Rainbow Creek 90222000 Iron2050 Highways - 2050 I-5 I-8 to La Jolla Village Dr Tecolote Creek 90650000 Cadmium

2050 Highways - 2050 I-5 SR 54 to I-15 Chollas Creek 90822000 Copper2050 Highways - 2050 I-5 SR 54 to I-15 Chollas Creek 90822000 Copper

2050 Highways - 2050 SR 15 I-5 to SR 94 Chollas Creek 90822000 Copper2050 Highways - 2050 SR 125 SR 905 to San Miguel Rd Pogi Canyon Creek 91020000 DDT2050 Transit LOSSAN 2050 San Diego River (Lower) 90711000 Fecal Coliform

2050 Transit LOSSAN 2050 San Marcos Creek 90451000 DDE2050 Transit LOSSAN 2050 San Luis Rey River 90311000 Chloride

2050 Transit LOSSAN 2050 Buena Vista Creek 90421000 Sediment Toxicity2050 Transit LOSSAN 2050 Los Peñasquitos Creek 90610000 Phosphate

2050 Transit LOSSAN 2050 Tecolote Creek 90650000 Cadmium2050 Transit LOSSAN 2050 San Luis Rey River 90311000 Chloride2050 Transit LOSSAN 2050 San Diego River (Lower) 90711000 Fecal Coliform



extend into the less populated areas at the edge of the highly urbanized areas. By 2050, most of the highway, transit, and active transportation (bicycle and pedestrian) improvements, along with other infrastructure projects, would be in place and operational in accordance with the proposed 2050 RTP/SCS. Some key highway improvements that would be in place by 2050 would include widening portions of SR 52, SR 56, SR 76, SR 94, SR 125, and I-5; additional HOV lanes and Managed Lanes along segments of I-805, I-5, I-15, SR 94, SR 125, and SR 54; and freeway and HOV connector improvements. Important transit improvements in place by 2050 would include the extension of Trolley lines and increased Trolley service frequency. The Trolley Green Line would be extended to Downtown-Bayside; a new Phase 2 of the line connecting San Diego State University to Downtown San Diego tovia El Cajon Boulevard/Mid-City would be constructedextended to San Diego State University; and a line from University Town Center to San Ysidro Palomar Trolley Station in the South Bay via Kearny Mesa, Mission Valley, Mid-City, and National City, and Chula Vista would be established. Table 4.10-4 shows the transportation improvements planned for 2050 that cross 303(d) listed water bodies and the impairments of these waters. As discussed in the 2020 analysis, specific regulations would apply to construction and the developed condition that require site-specific analysis of water quality issues and the incorporation of corresponding BMPs to control pollutant loads in project-related runoff. Compliance with these regulatory requirements would reduce these impacts to surface water and groundwater quality to less than significant. Conclusion

For 2050, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not violate water quality standards or WDRs, and this impact would be less than significant. WQ-2 DRAINAGE PATTERN ALTERATIONS

As discussed in 4.10.2, local regulations and standards are applied to project design and the practice of grading, clearing, and filling of land to ensure future land use and transportation projects are in compliance with applicable state and federal law. These requirements would include:

• Hydrologic and hydraulic calculations for proposed storm drains and for sizing of rock riprap energy dissipaters at storm drains to reduce storm runoff to nonerosive velocities,

• A SWPPP for any ground disturbance greater than 1 acre,

• A SWMP and Storm Water Maintenance Plan to include an erosion control plan showing appropriate BMPs to be installed and maintained during the course of construction,

• Preparation of landscape and irrigation plans for cut and fill slopes, and

• Installation of postconstruction BMPs prior to the acceptance of the grading plan by local agencies.

Construction associated with the proposed transportation network improvements would mostly involve disturbance along existing urbanized roadways. In accordance with the current (2003) Caltrans Storm Water Management Plan, various maintenance practices are employed to minimize erosion and sediment transport off freeway, highway, and roadway slopes, medians, and rights-of-way. These are generally classified as C Family maintenance activities. Accordingly, rights-of-way associated with the proposed freeway/highway transportation improvements would largely involve disturbing areas that are not



currently erosion-prone. Whether occurring along a freeway, highway, or local roadway, disturbances greater than 1 acre would be permitted through the State’s General Construction Permit (2009-0009-DWQ), which would serve to control erosion and sedimentation during construction, as well as requiring that postconstruction soil stabilization be proven before a Notice of Termination is granted. The General Construction Permit would also apply to land development projects implementing the 2050 RTP/SCS growth forecast. 2020


By 2020, population within the region is expected to increase by 310,568 people; housing by 113,062 units; and employment by 118,535 jobs. When comparing existing land use as shown in Figure 4.11-1 and 2020 land use as shown in Figure 4.11-3, no substantial differences occur in the land use patterns, types, or areas of development. Some locations that would experience the most extensive land use change and development by 2020 would include areas such as eastern Chula Vista along the SR 125 and I-805 corridors; San Diego community planning areas of San Ysidro and Otay Mesa along the SR 905 corridor; City of San Diego coastal and bay communities south of I-8, including Ocean Beach and the Peninsula planning areas; portions of northern Santee; areas north and south of the SR 56 corridor in the San Diego planning areas of Carmel Valley, Del Mar Mesa, Pacific Highlands Ranch, and Torrey Highlands; the San Marcos area near both the SR 78 and I-15 corridors; and within unincorporated County communities such as Fallbrook, Pala-Pauma Valley, and Valley Center along the I-15 and SR 76 corridors. This regional growth and associated development with the 2050 RTP/SCS may result in impacts to drainage patterns due to construction activity and increases in impervious areas especially on existing vacant land. Increases in impervious areas result in increased storm water flows in volume and/or velocity. Any increase in volume and/or velocity of storm water flow increases the potential for flooding, scouring, erosion, and other drainage pattern alterations. However, development associated with the 2050 RTP/SCS regional growth would have to comply with all existing regulations pertaining to drainage patterns (i.e., the local SUSMP and HMP). These regulations include the requirement that postproject storm water flows match the preproject flows for Priority Development Projects. When there is an increase in impervious area, this requirement would generally be achieved through the implementation of the appropriate BMPs described in the local SUSMP and HMP, and the County LID Handbook. Furthermore, drainage systems would be upgraded and increased in size in areas determined to have inadequate conveyance capacity relative to new impervious surface to reduce storm water runoff-related impacts. Impacts resulting from construction would be primarily addressed through compliance with the Construction General Permit as discussed in WQ-1. In addition, hydromodification regulations (i.e., Order R9-2007-0001) require that priority development projects maintain preproject hydrology under postconstruction operation. This means that additional runoff volumes and peak flow discharges from impervious areas, such as freeways, must be attenuated to preproject levels in order to maintain hydrological conditions and not exceed storm water conveyance capacities. One of the methods for achieving this is through the implementation of LID. LID is an integrated site design methodology that uses small-scale detention and retention to minimize pollutants conveyed by runoff and to mimic preproject site hydrological conditions. By incorporating these prescriptive design standards into the 2050 RTP/SCS projects, surface runoff patterns and flows would be controlled. However, where development occurs in erosion-prone areas, impacts could occur that are beyond the control of existing regulation. Therefore, development associated with land use changes identified in the 2050 RTP/SCS could substantially alter existing drainage patterns in a manner that would cause significant water quality impacts by 2020.



Transportation Network Improvements

The transportation network improvements that would be implemented between 2010 and 2020 generally include widening and/or installation of HOV lanes, and Managed Lanes, and Transit Lanes along portions of I-5, I-15, I-805, SR 78, and SR 94; completion of SR 905 and SR 11; and HOV connector projects along I-805 and SR 78 at I-15. Some key transit network improvements in place by 2020 would include increases in existing COASTER service, including extension of COASTER service to the San Diego Convention Center and Petco Park. BRT downtown express services from inland and south bay locations would be expanded as well as new BRT routes from the south bay area and along I-15. Rapid bus service would add new routes and streetcar routes would be established. Airport express routes would also be developed. Local bus service would be improved to 15 minutes in key corridors. Double-tracking of the LOSSAN rail corridor would occur to accommodate increased frequency in COASTER and other rail services that utilize this rail line. In addition, the new Mid-Coast Trolley line from Old Town to University Town Center would be constructed and the Green Trolley line would be extended to downtown San Diego. Refer to Table 4.10-2 for the transportation improvements planned for 2020 that cross 303(d) impaired water bodies. The 2050 RTP/SCS highway, arterial, transit, and active transportation (bicycle and pedestrian) improvements would result in impacts to drainage patterns without the incorporation of the appropriate BMPs. Grading and recontouring would be contingent on project alignments, existing topography, and the size/extent of runoff conveyance systems. While most of the transportation improvements would occur in already urbanized areas, some improvements would occur on vacant land and would likely cross natural drainage areas. Impacts to both upstream and downstream resources can result from alterations to streams, rivers, and floodways, such as increases in impervious areas and the construction of bridge pilings. The introduction of new or expanded bridge pilings can cause scouring and changes in the transportation and deposition of sediment both upstream and downstream. Impervious areas increase storm water flow volume and/or velocity, thereby increasing the potential for flooding, and scouring and erosion in channels. Current design practices employed in accordance with the local HMP, Caltrans standards, and other related regulations and programs require that engineered conveyances (whether hardscaped or soft bottom) integrate energy dissipation protection, streambank erosion protection, bridge pier scour protection, and other suitable design controls to minimize erosion or the transport of sediment or silt to downstream areas. By incorporating these standard engineering practices and complying with individual permits, general permits, and other applicable regulatory requirements (see WQ-1, above), significant erosion impacts on-site or off-site would be avoided. In some instances, where natural erosion has previously existed, project implementation could improve erosion control and reduce downstream sedimentation should project footprints coincide with such areas. Similar engineering standards exist for properly controlling and conveying surface runoff and surface waters when drainage modifications are necessary for project implementation. Caltrans drainage designs conform to the Highway Design Manual (Caltrans 2010), which requires the following criteria for a freeways and highways (i.e., roads with speeds greater than 45 mph):

• Roadway storm drain system and the freeway shoulder must be able to safely drain the 25-year return interval storm.

• Cross-Culverts must be designed to convey the 10-year interval storm (without the headwater depth being greater than the pipe height).



o The headwater depth for the 100-year interval storm must not overtop the freeway, as well as protecting private property outside of the freeway right-of-way from flooding.

The County of San Diego requires that transportation projects be designed to convey 50-year design storm peak runoff volumes within the project drainage system and capable of conveying 100-year floodwaters without exceeding curb height or damaging structures along the right-of-way (County of San Diego 2005). In addition, hydromodification regulations (i.e., Order R9-2007-0001) require that priority development projects maintain preproject hydrology under postconstruction operation. This means that additional runoff volumes and peak flow discharges from impervious areas, such as freeways, must be attenuated to preproject levels in order to maintain hydrological conditions and not exceed storm water conveyance capacities. One of the methods for achieving this is through the implementation of LID. LID is an integrated site design methodology that uses small-scale detention and retention to minimize pollutants conveyed by runoff and to mimic preproject site hydrological conditions. However, dependent upon the project specific alignment, such as areas with high erodibility, there could be impacts that are beyond the control of regulatory requirements. Therefore, despite incorporating the discussed design standards into the 2050 RTP/SCS projects, surface runoff patterns and flows may not be adequately controlled and impacts to drainage patterns from project-related facilities would be significant. Conclusion

By 2020, the forecasted land use changes and transportation network improvements associated with the implementation of the 2050 RTP/SCS have the potential to substantially alter drainage patterns in a manner that would cause significant water quality impacts. Adherence to existing regulatory requirements described above and in Section 4.10.2 would help reduce these impacts, but there is no assurance that they would reduce these impacts to a less than significant level. Therefore, this is a significant impact for which mitigation measures are described in Section 4.10.5. 2035


By 2035, the population of the region is expected to increase by 801,699 people; housing by 268,094 units; and employment by 312,292 jobs over existing 2010 conditions. As shown in Figure 4.11-4, regional land use and development changes are evident by 2035. Some locations that would experience the most extensive land use change and development by 2035 would include continued growth in eastern Chula Vista along the SR 125 and I-805 corridors; San Diego community planning areas of San Ysidro and Otay Mesa along the SR 905 and SR 125 corridors: northeast of the SR 94 corridor in the unincorporated County planning areas of Jamul/Dulzura, Tecate, and Potrero; eastern Poway along the SR 67 corridor; the County planning area of Ramona along the SR 67 and SR 78 corridors; the County planning areas of Lakeside and Alpine and the Crest, Granite Hills, Dehesa, Harbison Canyon subregion; and multiple north County planning areas along the 1-15 and SR 76 corridors such as Rainbow, Fallbrook, Bonsall, Pala-Pauma Valley, Valley Center, and Hidden Valley. The increased density can be seen when comparing the existing housing density to the 2035 housing density, as shown in Figures 4.13-2 and 4.13-8, respectively. Areas of increased residential density by 2035 would be apparent in some coastal cities such as Oceanside and Encinitas, and City of San Diego coastal communities. Also increased density would occur in more inland areas along the I-8 corridor through Mission Valley, College Area, and into the City of La Mesa, as well as eastern Chula Vista along the SR 125 corridor.



In the northern portion of the region, land use changes to accommodate growth in 2035 in the form of spaced rural residential development would occur along the I-15 corridor north of Escondido toward the northern county line and in more eastern areas along I-8, SR 67, SR 78, and SR 94. The SR 78 corridor, from Escondido to I-5 would experience growth and resulting land use density increases of both residential and commercial/office. As shown in Figure 4.11-4, single-family residential development would increase substantially along this corridor as well as additional commercial and industrial growth. The majority of this growth would be centered around the cities of Vista, San Marcos, and Escondido. The pattern of more dense growth along this segment of the SR 78 corridor is also apparent when comparing the existing housing density to 2035 housing density (see Figures 4.13.2 and 4.13-8 in Section 4.13, Population and Housing) and existing employment density to 2035 employment density (see Figures 4.13-3 and 4.13-9). By 2035, some regional growth would be accommodated in the more eastern, rural areas of the region. Development in these areas would be centered mostly along highway corridors, such as SR 78, SR 67, I-8 east of El Cajon, and SR 94, and generally within San Diego County community planning areas. The unincorporated portions of San Diego County are currently undergoing population growth and expansion of residential land use as indicated by a population increase of 14 percent from 2000 to 2010 as shown in Table 4.11-2. When comparing the existing land uses and 2035 land uses in Figures 4.11-1 and 4.11-4, the 2035 land use pattern would generally involve additional residential development in areas that were previously undeveloped open space or at some time in agricultural use (as discussed in Section 4.2). With the development occurring throughout the San Diego region, many of the impaired waters would be in the vicinity and possible ultimate discharge points for these projects. In these circumstances, BMPs would have to be selected to remove the pollutants that are impairing the water body. As discussed in the 2020 analysis, the effectiveness of the regulations to reduce the impacts of development depends upon the actual implementation of the requirements. By incorporating the required design standards and appropriately maintaining compliance with all applicable regulations for the 2050 RTP/SCS projects, surface runoff patterns and flows would be adequately controlled and impacts to drainage patterns would be reduced. However, because there could be impacts beyond the control of existing regulations, development associated with land use changes identified in the 2050 RTP/SCS could substantially alter existing drainage patterns in a manner that causes significant water quality impacts by 2035. Transportation Network Improvements

Some key highway improvements in place by 2035 would include continued widening along portions of I-5; additional HOV and Managed Lanes along portions of I-5, I-15, I-805, and SR 52; widening of portions of SR 125 and SR 67; and additional freeway and HOV connector improvements. Some important transit projects operational by 2035 would include continued increases in COASTER service, increases in SPRINTER service, increases in downtown area streetcar service, and substantial increases in rapid bus service throughout the region. The Trolley Blue Line would be extended from UTC to Mira Mesa via Sorrento Mesa and Carroll Canyon; the Orange Line would be extended to Lindbergh Field; Phase 1 of the new Mid-City to Downtown San Diego line would provide service from the Mid-City transit station via El Cajon Boulevard to Downtown; and a new line from Pacific Beach to El Cajon via Kearny Mesa, Mission Valley, and San Diego State University would be established. Double-tracking along the SPRINTER rail line through the cities of Oceanside, Vista, San Marco, and Escondido would take place by 2035 as well as continued double-tracking along the LOSSAN corridor. See Table 4.10-3 for the transportation improvements for 2035 that cross 303(d) listed water bodies.



As discussed in the 2020 analysis, the effectiveness of the regulations to reduce the impacts of development depends upon the actual implementation of the requirements. By incorporating the required design standards and complying with all applicable regulations for the 2050 RTP/SCS projects, surface runoff patterns and flows would be adequately controlled and impacts to drainage patterns would be reduced. However, because there could be impacts beyond the control of existing regulations, development associated with land use changes identified in the 2050 RTP/SCS could substantially alter existing drainage patterns in a manner that causes significant water quality impacts by 2035. Conclusion

By 2035, the forecasted land use changes and transportation network improvements associated with the implementation of the 2050 RTP/SCS have the potential to substantially alter drainage patterns in a manner that would cause significant water quality impacts. Adherence to existing regulatory requirements described above and in Section 4.10.2 would help reduce these impacts, but there is no assurance that they would reduce these impacts to a less than significant level. Therefore, this is a significant impact for which mitigation measures are described in Section 4.10.5. 2050


By 2050, the population of the region is forecast to increase by 1,160,435 people; housing by 379,664 units; and employment by 501,958 jobs over existing conditions. As shown in Figure 4.11-5, new growth and land use changes in 2050 per the 2050 RTP/SCS are apparent throughout the region. Areas of substantial land use change and development, beyond that described in 2035 would include significant industrial development in the County’s Otay planning area and San Diego Otay Mesa community surrounding the East Otay Mesa POE; throughout County planning areas located along the international border including Tecate, Potrero, Campo/Lake Morena, Boulevard, and Jacumba; throughout the Ramona and Julian planning areas in the unincorporated County; throughout other northeastern County planning areas, including North Mountain, Desert, and Borrego Springs; and continued development throughout County planning areas located north and east of Escondido extending to the northern border with Riverside County, including Rainbow, Fallbrook, Bonsall, Pala-Pauma Valley, Valley Center, Hidden Valley, Twin Oaks Valley, and North County Metro. Increased population density from 2010 through 2050 can be seen when comparing Figures 4.13-1, and 4.13-10, respectively. Increased density is most apparent in City of San Diego communities near the downtown area near I-5 and I-805 and along the I-8 corridor to the east. Urban centers in the western third of the San Diego region would have most available land developed with single- and multi-family uses, commercial and office uses, and industrial uses. Consistent with the goals of the 2050 RTP/SCS, the dense growth within existing urban centers with high accessibility to transit options allows for the creation of communities that are more sustainable, walkable, transit-oriented, and compact. Substantial dense growth within the urban centers corresponds with major transportation corridors such as I-5, I-8, I-15, and I-805 and these are also alignments that would have extensive transit opportunities. Similar to the description in the 2035 analysis, growth would continue in more eastern locations of the region, such as east of I-15 in the northern area, east of SR 67 through the middle portion of the region, and east of SR 94 in the southern area. However, by 2050, spaced rural residential development would have expanded beyond areas along existing transportation corridors and established rural communities and into areas with very minimal development at present. As shown in Figure 4.11-5, some of these areas



include northeast of Escondido to SR 76, areas east of Camp Pendleton, and areas north and south of the SR 78 corridor. As shown in Figure 4.11-5, by 2050, a substantial pocket of industrial development would be located along the planned SR 905 corridor in conjunction with the new Otay Mesa East POE at the international border with Mexico. This is a newly developing area that is planned for mainly industrial use and is highly dependent upon the planned construction of SR 11, SR 905, and the Otay Mesa East POE. With the development occurring throughout the San Diego region, many of the impaired waters would be in the vicinity and possible ultimate discharge points for these projects. In these circumstances, BMPs would have to be selected to remove the pollutants that are impairing the water body. As discussed in the 2020 analysis, the effectiveness of the regulations to reduce the impacts of development depends upon the actual implementation of the requirements. By incorporating the required design standards and appropriately maintaining compliance with all applicable regulations for the 2050 RTP/SCS projects, surface runoff patterns and flows would be adequately controlled and impacts to drainage patterns would be reduced. However, because there could be impacts beyond the control of existing regulations, development associated with land use changes identified in the 2050 RTP/SCS could substantially alter existing drainage patterns in a manner that causes significant water quality impacts by 2035. Transportation Network Improvements

Transportation improvements planned for 2050 are located throughout the western half of the San Diego region, but unlike the improvements planned by 2020 and 2035, several of these planned improvements extend into the less populated areas at the edge of the highly urbanized areas. By 2050, most of the highway, transit, and active transportation (bicycle and pedestrian) improvements, along with other infrastructure projects, would be in place and operational in accordance with the proposed 2050 RTP/SCS. Some key highway improvements that would be in place by 2050 would include widening portions of SR 52, SR 56, SR 76, SR 94, SR 125, and I-5; additional HOV lanes and Managed Lanes along segments of I-805, I-5, I-15, SR 94, SR 125, and SR 54; and freeway and HOV connector improvements. Important transit improvements in place by 2050 would include the extension of Trolley lines and increased Trolley service frequency. The Trolley Green Line would be extended to Downtown-Bayside; a new Phase 2 of the line connecting San Diego State University to Downtown San Diego tovia El Cajon Boulevard/Mid-City would be constructedextended to San Diego State University; and a line from University Town Center to San Ysidro Palomar Trolley Station in the South Bay via Kearny Mesa, Mission Valley, Mid-City, and National City, and Chula Vista would be established.

Refer to Figure 4.10-3 for the transportation improvements for 2035 that cross 303(d) listed water bodies. As discussed in the 2020 analysis, the effectiveness of the regulations to reduce the impacts of development depends upon the actual implementation of the requirements. By incorporating the required design standards and complying with all applicable regulations for the 2050 RTP/SCS projects, surface runoff patterns and flows would be adequately controlled and impacts to drainage patterns would be reduced. However, because there could be impacts beyond the control of existing regulations, development associated with land use changes identified in the 2050 RTP/SCS could substantially alter existing drainage patterns in a manner that causes significant water quality impacts by 2035. Conclusion

By 2050, the forecasted land use changes and transportation network improvements associated with the implementation of the 2050 RTP/SCS have the potential to substantially alter drainage patterns in a manner that would cause significant water quality impacts. Adherence to existing regulatory requirements



described above and in Section 4.10.2 would help reduce these impacts, but there is no assurance that they would reduce these impacts to a less than significant level. Therefore, this is a significant impact for which mitigation measures are described in Section 4.10.5. WQ-3 PLACING STRUCTURES IN 100-YEAR FLOOD HAZARD AREA

The 100-year flood hazard areas are shown in Figure 4.10-3. For the various projects proposed (particularly those projects located within an existing 100-year flood hazard area [Figure 4.10-3]), a project-specific hydrology study would be required to demonstrate compliance with local agency flood-control regulations. Increased flooding hazards due to potential climate change are discussed in Section 4.8, Greenhouse Gas Emissions and Global Climate Change. 2020


By 2020, population within the region is expected to increase by 310,568 people; housing by 113,062 units; and employment by 118,535 jobs. When comparing existing land use as shown in Figure 4.11-1 and 2020 land use as shown in Figure 4.11-3, no substantial differences occur in the land use patterns, types, or areas of development. Some locations that would experience the most extensive land use change and development by 2020 would include areas such as eastern Chula Vista along the SR 125 and I-805 corridors; San Diego community planning areas of San Ysidro and Otay Mesa along the SR 905 corridor; City of San Diego coastal and bay communities south of I-8, including Ocean Beach and the Peninsula planning areas; portions of northern Santee; areas north and south of the SR 56 corridor in the San Diego planning areas of Carmel Valley, Del Mar Mesa, Pacific Highlands Ranch, and Torrey Highlands; the San Marcos area near both the SR 78 and I-15 corridors; and within unincorporated County communities such as Fallbrook, Pala-Pauma Valley, and Valley Center along the I-15 and SR 76 corridors. The regional growth and land use changes associated with the 2050 RTP/SCS that are located within the existing floodplains would be impacted by a 100-year flood if appropriate design measures are not incorporated. However, existing regulations require that local hydraulic studies and risk assessments be performed where projects would encroach on a base floodplain or support incompatible floodplain development. When these studies indicate significant encroachment, the project development would be required to incorporate flood-safety design measures, such as the storm drain requirements and drainage pattern flow controls, to prevent redirecting or impeding flood flows. Additionally, where floodplain boundary revisions are unavoidable, a Conditional Letter of Map Revision (CLOMR) would be prepared and submitted to FEMA. Table 4.10-5 shows the proposed changes in land use types that encroach upon the 100-year floodplain for each horizon year. Each land use type included in the table reflects a parcel whose land use type is proposed to change in the 2050 RTP/SCS by the designated horizon year.

Table 4.10-5 Land Use Type Changes in the 100-year Floodplain

2020 2035 2050 Spaced Rural Residential Spaced Rural Residential Spaced Rural Residential Single Family Residential Single Family Residential Single Family Residential Single Family Detached Single Family Detached Single Family Detached Single Family Multiple-Units Single Family Multiple-Units Multi-Family Residential Single Family Residential Without Units Multi-Family Residential Mobile Home Park Multi-Family Residential Hotel/Motel (Low-Rise) Other Group Quarters Facility Multi-Family Residential Without Units Hotel/Motel (High-Rise) Hotel/Motel (Low-Rise) Mobile Home Park Resort Hotel/Motel (High-Rise) Jail/Prison Industrial Park Resort



2020 2035 2050 Dormitory Light Industry - General Heavy Industry Military Barracks General Aviation Airport Industrial Park Other Group Quarters Facility Rail Station/Transit Center Light Industry - General Hotel/Motel (Low-Rise) Parking Lot - Surface Warehousing Hotel/Motel (High-Rise) Road Right of Way Extractive Industry Resort Regional Shopping Center Junkyard/Dump/Landfill Heavy Industry Community Shopping Center General Aviation Airport Industrial Park Neighborhood Shopping Center Rail Station/Transit Center Light Industry - General Specialty Commercial Freeway Warehousing Arterial Commercial Communications and Utilities

Public Storage Other Retail Trade and Strip Commercial Parking Lot - Surface

Extractive Industry Office (Low-Rise) Railroad Right of Way General Aviation Airport Cemetery Road Right of Way Rail Station/Transit Center Fire/Police Station Marine Terminal Freeway Other Public Services Regional Shopping Center Communications and Utilities Other Health Care Community Shopping Center Parking Lot - Surface Other University or College Neighborhood Shopping Center Railroad Right of Way Senior High School Specialty Commercial Road Right of Way Elementary School Arterial Commercial Other Transportation Other Recreation - High Other Retail Trade and Strip Commercial Marine Terminal Park - Active Office (High-Rise) Regional Shopping Center Open Space Park or Preserve Office (Low-Rise) Community Shopping Center Vacant and Undeveloped Land Religious Facility Neighborhood Shopping Center Mixed Use Post Office Specialty Commercial Fire/Police Station Automobile Dealership Other Public Services Arterial Commercial Other Health Care Service Station Military Use Other Retail Trade and Strip Commercial Schools Office (Low-Rise) Other University or College Religious Facility Senior High School Library Elementary School Fire/Police Station Other Recreation - High Other Public Services Park - Active Hospital - General Open Space Park or Preserve Other Health Care Landscape Open Space Military Training Agriculture Other University or College Orchard or Vineyard Junior College Intensive Agriculture Senior High School Field Crops Junior High School or Middle School Lake/ Reservoir/Large Pond Elementary School Mixed Use Other School Racetrack Golf Course Golf Course Clubhouse Marina Other Recreation - High Park - Active Open Space Park or Preserve Beach - Active Beach - Passive Landscape Open Space Residential Recreation Undevelopable Natural Area Orchard or Vineyard Intensive Agriculture



2020 2035 2050 Field Crops Vacant and Undeveloped Land Water Bay or Lagoon Lake/ Reservoir/Large Pond Indian Reservation Public/Semi-Public Residential Under Construction Commercial Under Construction Industrial Under Construction Office Under Construction School Under Construction Mixed Use

Source: SANDAG 2011 Transportation Network Improvements

The transportation network improvements that would be implemented between 2010 and 2020 generally include widening and/or installation of HOV lanes, and Managed Lanes, and Transit Lanes along portions of I-5, I-15, I-805, SR 78, and SR 94; completion of SR 905 and SR 11; and HOV connector projects along I-805 and SR 78 at I-15. Some key transit network improvements in place by 2020 would include increases in existing COASTER service, including extension of COASTER service to the San Diego Convention Center and Petco Park. BRT downtown express services from inland and south bay locations would be expanded as well as new BRT routes from the south bay area and along I-15. Rapid bus service would add new routes and streetcar routes would be established. Airport express routes would also be developed. Local bus service would be improved to 15 minutes in key corridors. Double-tracking of the LOSSAN rail corridor would occur to accommodate increased frequency in COASTER and other rail services that utilize this rail line. In addition, the new Mid-Coast Trolley line from Old Town to University Town Center would be constructed and the Green Trolley line would be extended to downtown San Diego. By 2020, numerous highway, transit, and active transportation (bicycle and pedestrian) improvements are planned for the region in accordance with the 2050 RTP/SCS. Table 4.10-6 shows the transportation network improvements planned for 2020 that could encroach upon the 100-year floodplain. Every project would be required to comply with applicable state, county, or municipal flood-control regulations. All projects within the County of San Diego must comply with their Drainage Design Manual (County of San Diego 2005). Additionally, where floodplain boundary revisions are unavoidable, a Conditional Letter of Map Revision (CLOMR) would be prepared and submitted to FEMA. For federally funded projects, Caltrans design standards accommodate the pass-through conveyance of 100-year storm flows without impeding or redirecting the flows that could harm life and property. The requirements as defined by regulations have become more stringent and require that drainage systems be designed to have the capacity to convey larger volumes of runoff from larger storm events than was previously required. As a result, improvements to old roadways commonly result in an upgrade to the drainage systems and potential flood hazards can be decreased. By incorporating these and other mandatory design standards, the extent of 100-year flood events would not be redirected or impeded but could be reduced by the 2050 RTP/SCS facilities.



Table 4.10-6 Transportation Network Improvements Planned for 2020 in the 100-year Floodplain

Horizon Year

Improvement Type Improvement

2020 Arterials Willow Street Bridge Project - Bonita Road to Sweetwater Road 2020 Arterials El Camino Real and Cannon Road 2020 Arterials South Santa Fe - Bosstick to Smilax

2020 Arterials Borden Road Street Improvements and Bridge Construction - Twin Oaks to Woodward Street

2020 Arterials San Marcos Boulevard Street Improvements - Rancho Santa Fe to Bent Avenue 2020 Arterials Discovery Street Improvements - McMahr Rd to Bent Ave/Craven Road



2020 Arterials Bent Avenue Bridge - San Marcos Boulevard to Discovery Street 2020 Arterials Bear Valley Parkway North - San Pasqual Valley Road to Boyle Avenue 2020 Arterials Espola Road 2020 Arterials Bear Valley/East Valley/Valley Center - Citrus Avenue to Beven Drive 2020 Arterials El Camino Real 2020 Arterials El Camino Real - La Costa Avenue to Arenal Road 2020 Arterials Citracado Parkway II - West Valley to Harmony Grove 2020 Arterials South Santa Fe Avenue North - Montgomery Drive to South of Woodland Drive 2020 Arterials College Boulevard - Vista Way to Old Grove Road 2020 Arterials College Boulevard Bridge - San Luis Rey River 2020 Arterials South Santa Fe Avenue South - South of Woodland Drive to Smilax Road 2020 Highways SR I-15 from SR 94I-805 to I-8 2020 Highways SR 78 from I-5 to I-15 2020 Highways SR 76 from Melrose Drive to I-15 2020 Transit LOSSAN 2008 2020 Transit SPRINTER 2010 2020 Transit LOSSAN 2020

Source: SANDAG 2011

Conclusion

For 2020, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not place structures within a 100-year flood hazard zone that would impede or redirect flood flows, to the maximum extent practicable. However, conditions may arise where 100-year flood hazards cannot be avoided and redirection of flood flows may be necessary. Where flood hazards pose dangers to public safety, project-level designs would consider elevation changes for roadway features that avoid floodplain hazards. In such cases, floodplain boundary revisions would be necessary through the preparation of a Conditional Letter of Map Revision (CLOMR), which would be submitted to FEMA. Therefore, this impact is less than significant. 2035


By 2035, the population of the region is expected to increase by 801,699 people; housing by 268,094 units; and employment by 312,292 jobs over existing 2010 conditions. As shown in Figure 4.11-4, regional land use and development changes are evident by 2035. Some locations that would experience the most extensive land use change and development by 2035 would include continued growth in eastern Chula Vista along the SR 125 and I-805 corridors; San Diego community planning areas of San Ysidro and Otay Mesa along the SR 905 and SR 125 corridors: northeast of the SR 94 corridor in the



unincorporated County planning areas of Jamul/Dulzura, Tecate, and Potrero; eastern Poway along the SR 67 corridor; the County planning area of Ramona along the SR 67 and SR 78 corridors; the County planning areas of Lakeside and Alpine and the Crest, Granite Hills, Dehesa, Harbison Canyon subregion; and multiple north County planning areas along the 1-15 and SR 76 corridors such as Rainbow, Fallbrook, Bonsall, Pala-Pauma Valley, Valley Center, and Hidden Valley. The increased density can be seen when comparing the existing housing density to the 2035 housing density, as shown in Figures 4.13-2 and 4.13-8, respectively. Areas of increased residential density by 2035 would be apparent in some coastal cities such as Oceanside and Encinitas, and City of San Diego coastal communities. Also, increased density would occur in more inland areas along the I-8 corridor through Mission Valley, College Area, and into the City of La Mesa, as well as eastern Chula Vista along the SR 125 corridor. In the northern portion of the region, land use changes to accommodate growth in 2035 in the form of spaced rural residential development would occur along the I-15 corridor north of Escondido toward the northern county line and in more eastern areas along I-8, SR 67, SR 78, and SR 94. The SR 78 corridor, from Escondido to I-5, would experience growth and resulting land use density increases of both residential and commercial/office. As shown in Figure 4.11-4, single-family residential development would increase substantially along this corridor as well as additional commercial and industrial growth. The majority of this growth would be centered around the cities of Vista, San Marcos, and Escondido. The pattern of more dense growth along this segment of the SR 78 corridor is also apparent when comparing the existing housing density to 2035 housing density (see Figures 4.13.2 and 4.13-8 in Section 4.13, Population and Housing) and existing employment density to 2035 employment density (see Figures 4.13-3 and 4.13-9). By 2035, some regional growth would be accommodated in the more eastern, rural areas of the region. Development in these areas would be centered mostly along highway corridors, such as SR 78, SR 67, I-8 east of El Cajon, and SR 94, and generally within San Diego County community planning areas. The unincorporated portions of San Diego County are currently undergoing population growth and expansion of residential land use as indicated by a population increase of 14 percent from 2000 to 2010 as shown in Table 4.11-2. When comparing the existing land uses and 2035 land uses in Figures 4.11-1 and 4.11-4, the 2035 land use pattern would generally involve additional residential development in areas that were previously undeveloped open space or at some time in agricultural use (as discussed in Section 4.2). As discussed in the 2020 analysis, development planned for 2035 associated with the 2050 RTP/SCS could be impacted by the existing 100-year floodplain unless appropriate design measures are incorporated. These design measures would reduce impacts due to redirecting or impeding flood flows to below a level of significance. Refer to Table 4.10-5 for the proposed changes in land use types that encroach upon the 100-year floodplain for 2035. Transportation Network Improvements

Some key highway improvements in place by 2035 would include continued widening along portions of I-5; additional HOV and Managed Lanes along portions of I-5, I-15, I-805, and SR 52; widening of portions of SR 125 and SR 67; and additional freeway and HOV connector improvements. Some important transit projects operational by 2035 would include continued increases in COASTER service, increases in SPRINTER service, increases in downtown area streetcar service, and substantial increases in rapid bus service throughout the region. The Trolley Blue Line would be extended from UTC to Mira Mesa via Sorrento Mesa and Carroll Canyon; the Orange Line would be extended to Lindbergh Field; Phase 1 of the new Mid-City to Downtown San Diego line would provide service from the Mid-City transit station via El Cajon Boulevard to Downtown; and a new line from Pacific Beach to El Cajon via



Kearny Mesa, Mission Valley, and San Diego State University would be established. Double-tracking along the SPRINTER rail line through the cities of Oceanside, Vista, San Marco, and Escondido would take place by 2035 as well as continued double-tracking along the LOSSAN corridor. By 2035, numerous highway, transit, and active transportation (bicycle and pedestrian) improvements, along with other infrastructure projects, are planned for the region in accordance with the 2050 RTP/SCS. Table 4.10-7 shows the transportation network improvements planned for 2035 that could encroach upon the 100-year floodplain. As discussed in the 2020 analysis, every project would be required to comply with pertinent state, county, or municipal regulations. By incorporating these and other mandatory design standards, the extent of 100-year flood events would not be redirected or impeded but could be reduced by the 2050 RTP/SCS facilities.

Conclusion

For 2035, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not place structures within a 100-year flood hazard zone that would impede or redirect flood flows to the maximum extent practicable. However, conditions may arise where 100-year flood hazards cannot be avoided and redirection of flood flows may be necessary. Where flood hazards pose dangers to public safety, project-level designs would consider elevation changes for roadway features that avoid floodplain hazards. In such cases, floodplain boundary revisions would be necessary through the preparation of a Conditional Letter of Map Revision (CLOMR), which would be submitted to FEMA. . Therefore, this impact is less than significant.


Horizon Year


2035 Arterials Genesee Avenue - Nobel Drive to SR 52

2035 Highways I-5 from SR 56 to Manchester Ave

2035 Highways SR 67 from Mapleview St to Dye Road

2035 Highways I-15 from SR 94 to I-805

2035 Transit LPA Mid-Coast Trolley (510)Centerline

2035 Transit LOSSAN 2030

2035 Transit LRT Extensions

2035 Transit SPRINTER 2035 Source: SANDAG 2011

2050


By 2050, the population of the region is forecast to increase by 1,160,435 people; housing by 379,664 units; and employment by 501,958 jobs over existing conditions. As shown in Figure 4.11-5, new growth and land use changes in 2050 per the 2050 RTP/SCS are apparent throughout the region. Areas of substantial land use change and development, beyond that described in 2035 would include significant industrial development in the County’s Otay planning area and San Diego Otay Mesa community surrounding the East Otay Mesa POE; throughout County planning areas located along the international border including Tecate, Potrero, Campo/Lake Morena, Boulevard, and Jacumba; throughout the Ramona and Julian planning areas in the unincorporated County; throughout other northeastern County planning areas, including North Mountain, Desert, and Borrego Springs; and continued development throughout



County planning areas located north and east of Escondido extending to the northern border with Riverside County, including Rainbow, Fallbrook, Bonsall, Pala-Pauma Valley, Valley Center, Hidden Valley, Twin Oaks Valley, and North County Metro. Increased population density from 2010 through 2050 can be seen when comparing Figures 4.13-1, and 4.13-10, respectively. Increased density is most apparent in City of San Diego communities near the downtown area near I-5 and I-805 and along the I-8 corridor to the east. Urban centers in the western third of the San Diego region would have most available land developed with single- and multi-family uses, commercial and office uses, and industrial uses. Consistent with the goals of the 2050 RTP/SCS, the dense growth within existing urban centers with high accessibility to transit options allows for the creation of communities that are more sustainable, walkable, transit-oriented, and compact. Substantial dense growth within the urban centers corresponds with major transportation corridors such as I-5, I-8, I-15, and I-805 and these are also alignments that would have extensive transit opportunities. Similar to the description in the 2035 analysis, growth would continue in more eastern locations of the region, such as east of I-15 in the northern area, east of SR 67 through the middle portion of the region, and east of SR 94 in the southern area. However, by 2050, spaced rural residential development would have expanded beyond areas along existing transportation corridors and established rural communities and into areas with very minimal development at present. As shown in Figure 4.11-5, some of these areas include northeast of Escondido to SR 76, areas east of Camp Pendleton, and areas north and south of the SR 78 corridor. As shown in Figure 4.11-5, by 2050, a substantial pocket of industrial development would be located along the planned SR 905 corridor in conjunction with the new Otay Mesa East POE at the international border with Mexico. This is a newly developing area that is planned for mainly industrial use and is highly dependent upon the planned construction of SR 11, SR 905, and the Otay Mesa East POE. As discussed in the 2020 analysis, development planned for 2050 that is associated with the 2050 RTP/SCS could be impacted by the existing 100-year floodplain unless appropriate design measures are incorporated. These design measures would reduce impacts due to redirecting or impeding flood flows to below a level of significance. Refer to Table 4.10-5 for the proposed changes in land use types that encroach upon the 100-year floodplain for 2050. Transportation Network Improvements




By 2050, numerous highway, transit, and active transportation (bicycle and pedestrian) improvements, along with other infrastructure projects, are planned for the region in accordance with the 2050 RTP/SCS. Table 4.10-8 shows the transportation network improvements planned for 2050 that could encroach upon the 100-year floodplain. As discussed in the 2020 analysis, every project would be required to comply with pertinent state, county, or municipal regulations. By incorporating these and other mandatory design standards, the extent of 100-year flood events would not be redirected or impeded but could be reduced by the 2050 RTP/SCS facilities.

Conclusion

For 2050, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not place structures within a 100-year flood hazard zone that would impede or redirect flood flows to the maximum extent practicable. However, conditions may arise where 100-year flood hazards cannot be avoided and redirection of flood flows may be necessary. Where flood hazards pose dangers to public safety, project-level designs would consider elevation changes for roadway features that avoid floodplain hazards. In such cases, floodplain boundary revisions would be necessary through the preparation of a Conditional Letter of Map Revision (CLOMR), which would be submitted to FEMA. . Therefore, this impact is less than significant. WQ-4 FLOOD HAZARDS

The 100-year flood hazard areas for the region are shown in Figure 4.10-3. In addition, local agency maps and regulations can be used to identify areas that would be subject to flooding from failure of a levee or dam. Impacts resulting from development associated with the 2050 RTP/SCS would be considered significant should they expose people or structures to a significant risk of loss, injury, or death involving flooding, including flooding as a result of the failure of a levee or dam.


Horizon Year


2050 Highways SR 52 from I-15 to SR 125 2050 Highways SR 56 from I-5 to I-15 2050 Highways SR 94 from I-805 to College Avenue 2050 Highways I-5 from SR 54 to I-15 2050 Highways I-5 from I-8 to La Jolla Village Drive 2050 Highways SR 15 from I-5 to SR 94 2050 Highways SR 54 from I-5 to SR 125 2050 Highways SR 125 from San Miguel Road to SR 54 2050 Highways SR 125 from SR 54 to SR 94 2050 Highways SR 76 from I-15 to Couser Canyon 2050 Highways SR 94 from Jamacha Rd to Steele Canyon Road 2050 Transit LOSSAN 2050 2050 Transit LRT Extensions

Source: SANDAG 2011



There are 25 surface water reservoirs and dams within SDCWA’s service area. Though more dams exist in the region, these are large reservoirs that could produce large volumes of water if a dam were to fail. The reservoirs and their storage volumes are shown in Table 4.10-9.

Table 4.10-9 Reservoirs with Dams within the SDCWA’s Service Area

Lake Storage

acre-feet) Maerkle 287 Dixon 2,305

Wohlford 2,531 Red Mountain 874

Cuyamaca 2,108 Jennings 8,854 Poway 3,150 Beck 152

Morro Hill 0 Ramona 2,715

Olivenhain - CWA 19,971 Barrett 34,408

El Capitan 104,101 Hodges 29,761

Lower Otay 42,799 Miramar 5,521 Morena 13,234 Murray 3,818

San Vicente 40,150 Sutherland 20,770

San Dieguito 620 Loveland 25,400

Sweetwater 19,819 Turner 1,612

Henshaw 20,548

In addition, there is potential for increased flooding hazards due to climate change. Climate change is expected to result in sea level rise due to expanding ocean water and melting ice from glaciers and ice caps. The International Panel on Climate Change (IPCC) estimates that the global average sea level will could rise between 7-24 inches in the next century (IPCC 2007), while in the San Diego region, sea level is projected to could rise by 12-18 inches by 2050 (San Diego Foundation 2008) Rising sea levels have a number of effects especially in low-lying regions, including intensifying erosion and flooding. Many of the effects of sea level rise in the San Diego region are expected to occur in coastal areas (San Diego Foundation 2008). This could result in loss of beach and recreational areas, and inundate wetlands. Beach loss increases vulnerability to storms and increased high tide and flooding risk. In more developed areas, street flooding and erosion near infrastructure could result in additional damage. Although the below evaluation stops at the 2050 RTP/SCS and EIR horizon year of 2050, it should be recognized that risks to development and transportation projects from sea level rise are projected to increase through 2100 and beyond unless appropriate adaptation strategies are implemented. 2020


By 2020, population within the region is expected to increase by 310,568 people; housing by 113,062 units; and employment by 118,535 jobs. When comparing existing land use as shown in Figure 4.11-1



and 2020 land use as shown in Figure 4.11-3, no substantial differences occur in the land use patterns, types, or areas of development. Some locations that would experience the most extensive land use change and development by 2020 would include areas such as eastern Chula Vista along the SR 125 and I-805 corridors; San Diego community planning areas of San Ysidro and Otay Mesa along the SR 905 corridor; City of San Diego coastal and bay communities south of I-8, including Ocean Beach and the Peninsula planning areas; portions of northern Santee; areas north and south of the SR 56 corridor in the San Diego planning areas of Carmel Valley, Del Mar Mesa, Pacific Highlands Ranch, and Torrey Highlands; the San Marcos area near both the SR 78 and I-15 corridors; and within unincorporated County communities such as Fallbrook, Pala-Pauma Valley, and Valley Center along the I-15 and SR 76 corridors. This development associated with the 2050 RTP/SCS could increase flood hazards without the appropriate design measures. Refer to Table 4.10-5 for the proposed changes in land use types that encroach upon the 100-year floodplain for 2020. The impacts of flooding due to climate change in the San Diego region are uncertain but are likely to affect coastal and wetland areas the greatest (San Diego Foundation 2008). Increased flooding is expected under climate change, with the primary areas impacted being wetlands and coastal regions. Under the 2050 RTP/SCS, additional development is projected in coastal and bay communities that have been shown to be vulnerable to sea level rise and flooding events. However, all drainage designs would be made to conform to the flood control requirements of the applicable jurisdiction. All development would be required to comply with the local SUSMP and HMP. The County of San Diego provides the Flood Control Hydrology Manual and Drainage Manual (County of San Diego 2005) for guidance on projects in the San Diego region. Public drainage facilities would be designed to convey the peak discharge of the 50-year flood event within the underground piping and the 100-year flood event to the top of the curb without damage to property adjacent to the right-of-way (County of San Diego 2005). Culverts in public roads would be designed to convey the peak discharge from the 100-year flood event. These requirements would include evaluation of potential flooding events, which include flooding as a result of climate change impacts that could occur in the long-term (e.g., the year 2100). Implementation of these design measures in development associated with the 2050 RTP/SCS would ensure flood hazards would be less than significant. Transportation Network Improvements

The transportation network improvements that would be implemented between 2010 and 2020 generally include widening and/or installation of HOV lanes, and Managed Lanes, and Transit Lanes along portions of I-5, I-15, I-805, SR 78, and SR 94; completion of SR 905 and SR 11; and HOV connector projects along I-805 and SR 78 at I-15. Some key transit network improvements in place by 2020 would include increases in existing COASTER service, including extension of COASTER service to the San Diego Convention Center and Petco Park. BRT downtown express services from inland and south bay locations would be expanded as well as new BRT routes from the south bay area and along I-15. Rapid bus service would add new routes and streetcar routes would be established. Airport express routes would also be developed. Local bus service would be improved to 15 minutes in key corridors. Double-tracking of the LOSSAN rail corridor would occur to accommodate increased frequency in COASTER and other rail services that utilize this rail line. In addition, the new Mid-Coast Trolley line from Old Town to University Town Center would be constructed and the Green Trolley line would be extended to downtown San Diego. These transportation network improvements could be exposed to flood hazards without the appropriate design measures. Refer to Table 4.10-6 for the transportation network improvements planned for 2020 that could encroach upon the 100-year floodplain. The effects of flooding as a result of climate change have not been fully analyzed for the San Diego region; however, increased flooding is expectedcould occur especially in coastal regions (San Diego Foundation 2008). Although most transportation network



improvement projects in the 2050 RTP/SCS for 2020 include expansion of existing networks, local bus and streetcar routes could be located in areas prone to flooding. County and municipal engineering standards require analysis of floodplain exposure and impacts to people and structures. Design protocols (defined in Section 4.10.2 above) require designers of transportation facilities to minimize the risk of property loss, injury, or death from flooding events, including flooding that may result from climate change. Given federal, state, and local engineering design requirements (e.g., Caltrans SWMP, SUSMP, and HMP), additional runoff from new or improved transportation facilities would be conveyed in a way to adequately protect downstream flood control structures and other applicable reservoir dams. Implementation of appropriate design measures in development associated with the 2050 RTP/SCS would ensure flood risks, including those associated with climate change, would be less than significant. These design measures would incorporate any applicable information regarding flooding resulting from climate change that could occur in the long-term (e.g., the year 2100). Accordingly, the construction and implementation of the 2050 RTP/SCS would have less than significant impacts in respect to flood hazards. Conclusion

For 2020, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not expose people or structures to a significant risk of loss, injury, or death from flooding. Therefore, this impact is less than significant. 2035


By 2035, the population of the region is expected to increase by 801,699 people; housing by 268,094 units; and employment by 312,292 jobs over existing 2010 conditions. As shown in Figure 4.11-4, regional land use and development changes are evident by 2035. Some locations that would experience the most extensive land use change and development by 2035 would include continued growth in eastern Chula Vista along the SR 125 and I-805 corridors; San Diego community planning areas of San Ysidro and Otay Mesa along the SR 905 and SR 125 corridors: northeast of the SR 94 corridor in the unincorporated County planning areas of Jamul/Dulzura, Tecate, and Potrero; eastern Poway along the SR 67 corridor; the County planning area of Ramona along the SR 67 and SR 78 corridors; the County planning areas of Lakeside and Alpine and the Crest, Granite Hills, Dehesa, Harbison Canyon subregion; and multiple north County planning areas along the 1-15 and SR 76 corridors such as Rainbow, Fallbrook, Bonsall, Pala-Pauma Valley, Valley Center, and Hidden Valley. The increased density can be seen when comparing the existing housing density to the 2035 housing density, as shown in Figures 4.13-2 and 4.13-8, respectively. Areas of increased residential density by 2035 would be apparent in some coastal cities such as Oceanside and Encinitas, and City of San Diego coastal communities. Also, increased density would occur in more inland areas along the I-8 corridor through Mission Valley, College Area, and into the City of La Mesa, as well as eastern Chula Vista along the SR 125 corridor. In the northern portion of the region, land use changes to accommodate growth in 2035 in the form of spaced rural residential development would occur along the I-15 corridor north of Escondido toward the northern county line and in more eastern areas along I-8, SR 67, SR 78, and SR 94. The SR 78 corridor, from Escondido to I-5, would experience growth and resulting land use density increases of both residential and commercial/office. As shown in Figure 4.11-4, single-family residential development would increase substantially along this corridor as well as additional commercial and industrial growth.



The majority of this growth would be centered around the cities of Vista, San Marcos, and Escondido. The pattern of more dense growth along this segment of the SR 78 corridor is also apparent when comparing the existing housing density to 2035 housing density (see Figures 4.13.2 and 4.13-8 in Section 4.13, Population and Housing) and existing employment density to 2035 employment density (see Figures 4.13-3 and 4.13-9). By 2035, some regional growth would be accommodated in the more eastern, rural areas of the region. Development in these areas would be centered mostly along highway corridors, such as SR 78, SR 67, I-8 east of El Cajon, and SR 94, and generally within San Diego County community planning areas. The unincorporated portions of San Diego County are currently undergoing population growth and expansion of residential land use as indicated by a population increase of 14 percent from 2000 to 2010 as shown in Table 4.11-2. When comparing the existing land uses and 2035 land uses in Figures 4.11-1 and 4.11-4, the 2035 land use pattern would generally involve additional residential development in areas that were previously undeveloped open space or at some time in agricultural use (as discussed in Section 4.2). Refer to Table 4.10-5 for the proposed changes in land use types that encroach upon the 100-year floodplain for 2035. As discussed in the 2020 analysis, these increases would spur development associated with the 2050 RTP/SCS, which could increase flood hazards without the appropriate design measures. Flooding and sea level rise impacts in 2035 would be more severe than in 2020, with higher sea level expected. Additional development is also expected in coastal areas under the 2050 RTP/SCS, which are the areas most susceptible to flooding. However, as discussed in the 2020 analysis, drainage designs would be made to conform to the flood control requirements of the applicable jurisdiction, including any applicable information regarding flooding resulting from climate change that could occur in the long-term (e.g., the year 2100).. Implementation of these design measures in development associated with the 2050 RTP/SCS would ensure flood risks would be less than significant. Transportation Network Improvements

Some key highway improvements in place by 2035 would include continued widening along portions of I-5; additional HOV and Managed Lanes along portions of I-5, I-15, I-805, and SR 52; widening of portions of SR 125 and SR 67; and additional freeway and HOV connector improvements. Some important transit projects operational by 2035 would include continued increases in COASTER service, increases in SPRINTER service, increases in downtown area streetcar service, and substantial increases in rapid bus service throughout the region. The Trolley Blue Line would be extended from UTC to Mira Mesa via Sorrento Mesa and Carroll Canyon; the Orange Line would be extended to Lindbergh Field; Phase 1 of the new Mid-City to Downtown San Diego line would provide service from the Mid-City transit station via El Cajon Boulevard to Downtown; and a new line from Pacific Beach to El Cajon via Kearny Mesa, Mission Valley, and San Diego State University would be established. Double-tracking along the SPRINTER rail line through the cities of Oceanside, Vista, San Marco, and Escondido would take place by 2035 as well as continued double-tracking along the LOSSAN corridor. Table 4.10-7 shows the transportation network improvements planned for 2035 that could encroach upon the 100-year floodplain. As discussed in the 2020 analysis, the transportation network improvements could be exposed to flood hazards without the appropriate design measures. Many of the 2050 RTP/SCS includes transportation network improvements include expansion of existing roadways and additional construction in non-coastal areas of the San Diego Region. However, due to the uncertainty in flooding effects from climate change, some of the proposed transportation network improvements could be located in regions prone to flooding under climate change. However, as discussed in the 2020 analysis, implementation of appropriate design measures in development associated with the 2050 RTP/SCS would ensure flood risks, including those associated with climate change, would be less than significant. These



design measures would incorporate any applicable information regarding flooding resulting from climate change that could occur in the long-term (e.g., the year 2100).. Conclusion

For 2035, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not expose people or structures to a significant risk of loss, injury, or death from flooding. Therefore, this impact is less than significant. 2050


By 2050, the population of the region is forecast to increase by 1,160,435 people; housing by 379,664 units; and employment by 501,958 jobs over existing conditions. As shown in Figure 4.11-5, new growth and land use changes in 2050 per the 2050 RTP/SCS are apparent throughout the region. Areas of substantial land use change and development, beyond that described in 2035 would include significant industrial development in the County’s Otay planning area and San Diego Otay Mesa community surrounding the East Otay Mesa POE; throughout County planning areas located along the international border including Tecate, Potrero, Campo/Lake Morena, Boulevard, and Jacumba; throughout the Ramona and Julian planning areas in the unincorporated County; throughout other northeastern County planning areas, including North Mountain, Desert, and Borrego Springs; and continued development throughout County planning areas located north and east of Escondido extending to the northern border with Riverside County, including Rainbow, Fallbrook, Bonsall, Pala-Pauma Valley, Valley Center, Hidden Valley, Twin Oaks Valley, and North County Metro. Increased population density from 2010 through 2050 can be seen when comparing Figures 4.13-1, and 4.13-10, respectively. Increased density is most apparent in City of San Diego communities near the downtown area near I-5 and I-805 and along the I-8 corridor to the east. Urban centers in the western third of the San Diego region would have most available land developed with single- and multi-family uses, commercial and office uses, and industrial uses. Consistent with the goals of the 2050 RTP/SCS, the dense growth within existing urban centers with high accessibility to transit options allows for the creation of communities that are more sustainable, walkable, transit-oriented, and compact. Substantial dense growth within the urban centers corresponds with major transportation corridors such as I-5, I-8, I-15, and I-805 and these are also alignments that would have extensive transit opportunities. Similar to the description in the 2035 analysis, growth would continue in more eastern locations of the region, such as east of I-15 in the northern area, east of SR 67 through the middle portion of the region, and east of SR 94 in the southern area. However, by 2050, spaced rural residential development would have expanded beyond areas along existing transportation corridors and established rural communities and into areas with very minimal development at present. As shown in Figure 4.11-5, some of these areas include northeast of Escondido to SR 76, areas east of Camp Pendleton, and areas north and south of the SR 78 corridor. As shown in Figure 4.11-5, by 2050, a substantial pocket of industrial development would be located along the planned SR 905 corridor in conjunction with the new Otay Mesa East POE at the international border with Mexico. This is a newly developing area that is planned for mainly industrial use and is highly dependent upon the planned construction of SR 11, SR 905, and the Otay Mesa East POE.



By 2050, additional growth and development are anticipated within the region over that which is forecasted by 2020 and 2035. From 2035 to 2050, the population of the region is expected to increase by 358,736 people; housing by 111,570 units; and employment by 189,666 jobs. From the base year 2010, this represents a total increase of population by 1,160,435 people; housing by 379,664 units; and employment by 501,958 jobs. Refer to Table 4.10-5 for the proposed changes in land use types that encroach upon the 100-year floodplain for 2050. In addition, flooding potential due to climate change would be more severe than in 2020 or 2035. However, regional growth/land use would generally be in regions not highly susceptible to flooding, such as coastal areas, in 2050; however, some development may occur in wetland, coastal, or other areas prone to flooding as a result of climate change. As discussed in the 2020 analysis, these increases would spur development associated with the 2050 RTP/SCS, which could increase flood hazards that could occur in the long-term (e.g., the year 2100). without the appropriate design measures. Implementation of these design measures in development associated with the 2050 RTP/SCS would ensure flood risks would be less than significant. Transportation Network Improvements


Table 4.10-8 shows the transportation network improvements planned for 2050 that could encroach upon the 100-year floodplain. In addition, sea level rise is expected to be 12-18 inches in the San Diego region by 2050, exposing low-lying areas to flooding. Most transportation network improvements in 2050 are expected to be on existing roadways or in non-coastal areas, but there could be some improvements in areas susceptible to flooding, such as wetland regions. As discussed in the 2020 analysis, the transportation network improvements could be exposed to flood hazards without the appropriate design measures. However, implementation of these design measures in development associated with the 2050 RTP/SCS would ensure flood risks, including those resulting from climate change, would be less than significant. These design measures would incorporate any applicable information regarding flooding resulting from climate change that could occur in the long-term (e.g., the year 2100) Conclusion

For 2050, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not expose people or structures to a significant risk of loss, injury, or death from flooding. Therefore, this impact is less than significant.



WQ-5 SEICHE, TSUNAMI, OR MUDFLOW

This impact generally results from seismic activity affecting enclosed or partially enclosed bodies of water (seiche), the county’s coastline (tsunami), and water-saturated steep slopes that contains loose soil or debris (mudflow). The potential inundation from a tsunami would be confined to the low-lying areas in the western part of the Coastal Zone. The California Department of Conservation has maps (CADC 2011) showing the areas of inundation from tsunamis for the San Diego region that can be used to determine whether a project footprint lies within the limits of inundation. Large enclosed or partially enclosed water bodies, such as the coastal bays and lakes, would be susceptible to seiche. Seiche can be caused by several factors including tsunami, earthquake, and wind. Though there are no current related regulations, there is no historical precedence for large damaging seiches in the San Diego region. Any development constructed adjacent to unstable slopes would be susceptible to mudflows. Current state and local design standards require slope stabilization that would reduce the possibility for mudflows. Future developments would undergo a project-specific analysis in which these standards would be applied to minimize mudflow risk. 2020


By 2020, population within the region is expected to increase by 310,568 people; housing by 113,062 units; and employment by 118,535 jobs. When comparing existing land use as shown in Figure 4.11-1 and 2020 land use as shown in Figure 4.11-3, no substantial differences occur in the land use patterns, types, or areas of development. Some locations that would experience the most extensive land use change and development by 2020 would include areas such as eastern Chula Vista along the SR 125 and I-805 corridors; San Diego community planning areas of San Ysidro and Otay Mesa along the SR 905 corridor; City of San Diego coastal and bay communities south of I-8, including Ocean Beach and the Peninsula planning areas; portions of northern Santee; areas north and south of the SR 56 corridor in the San Diego planning areas of Carmel Valley, Del Mar Mesa, Pacific Highlands Ranch, and Torrey Highlands; the San Marcos area near both the SR 78 and I-15 corridors; and within unincorporated County communities such as Fallbrook, Pala-Pauma Valley, and Valley Center along the I-15 and SR 76 corridors. This 2050 RTP/SCS-related development could expose people and property to seiche, tsunami, and mudflow. Development with project footprints that lie in low elevations directly adjacent to the coast would be susceptible to tsunami. Any development constructed adjacent to large enclosed or partially enclosed water bodies, such as the coastal bays and lakes, would be susceptible to seiche. However, there will not be significant land use changes around the coastal bays and all the lakes in the San Diego region are man-made structures maintained for the water storage and other beneficial uses. As such, there are no proposed changes to the land uses directly adjacent to the lake structures relating to the lake recreation. Any development constructed adjacent to unstable slopes would be susceptible to mudflows. Current state and local design standards require slope stabilization that would reduce the possibility for mudflows. Future developments would undergo a project-specific analysis in which these standards would be applied to minimize mudflow risk. Because land use and transportation projects are expected to occur in areas subject to these hazards, existing planning and design standards and regulations would serve to address and minimize the



associated potential impacts. Accordingly, project-specific technical studies, existing and updated emergency evacuation plans, water tank safety requirements, and other similar and applicable safety design considerations would be required to reduce potential risk associated with the 2050 RTP/SCS to levels of insignificance. Based on the above analysis, people or structures would not be exposed to a significant risk of inundation due to seiche, tsunami, or mudflow from development associated with the 2050 RTP/SCS. Transportation Network Improvements

The transportation network improvements that would be implemented between 2010 and 2020 generally include widening and/or installation of HOV lanes, and Managed Lanes, and Transit Lanes along portions of I-5, I-15, I-805, SR 78, and SR 94; completion of SR 905 and SR 11; and HOV connector projects along I-805 and SR 78 at I-15. Some key transit network improvements in place by 2020 would include increases in existing COASTER service, including extension of COASTER service to the San Diego Convention Center and Petco Park. BRT downtown express services from inland and south bay locations would be expanded as well as new BRT routes from the south bay area and along I-15. Rapid bus service would add new routes and streetcar routes would be established. Airport express routes would also be developed. Local bus service would be improved to 15 minutes in key corridors. Double-tracking of the LOSSAN rail corridor would occur to accommodate increased frequency in COASTER and other rail services that utilize this rail line. In addition, the new Mid-Coast Trolley line from Old Town to University Town Center would be constructed and the Green Trolley line would be extended to downtown San Diego. The highway, arterial, transit, and active transportation (bicycle and pedestrian) improvements could be exposed to impacts from seiches, tsunamis, and mudflows. Future transportation facilities would undergo a project-specific analysis in which existing standards would be applied to minimize risks from seiche, tsunami, or mudflow. Although impacts associated with mudflow damages would occur where transportation facilities are constructed adjacent to elevated terrain that is subject to instability, current design standards require slope stabilization that would reduce or avoid these potential impacts. Even though there are no transportation facility design standards or regulatory requirements for seiches, tsunamis, or mudflows, the forces induced by these events are unlikely to exceed those associated with large magnitude earthquakes for which modern California structures are designed to withstand. In addition, because the 2050 RTP/SCS projects would be capable of conveying 100-year flood waters, seiche or tsunami flows within these design parameters would be sufficiently conveyed. Based on the above analysis and compliance with the regulations outlined above, people or structures would not be exposed to a significant risk of inundation due to seiche, tsunami, or mudflow from development associated with the 2050 RTP/SCS. Conclusion

For 2020, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not expose people or structures to a significant risk of inundation due to seiche, tsunami, or mudflow. Therefore, this impact is less than significant.



2035


By 2035, the population of the region is expected to increase by 801,699 people; housing by 268,094 units; and employment by 312,292 jobs over existing 2010 conditions. As shown in Figure 4.11-4, regional land use and development changes are evident by 2035. Some locations that would experience the most extensive land use change and development by 2035 would include continued growth in eastern Chula Vista along the SR 125 and I-805 corridors; San Diego community planning areas of San Ysidro and Otay Mesa along the SR 905 and SR 125 corridors: northeast of the SR 94 corridor in the unincorporated County planning areas of Jamul/Dulzura, Tecate, and Potrero; eastern Poway along the SR 67 corridor; the County planning area of Ramona along the SR 67 and SR 78 corridors; the County planning areas of Lakeside and Alpine and the Crest, Granite Hills, Dehesa, Harbison Canyon subregion; and multiple north County planning areas along the 1-15 and SR 76 corridors such as Rainbow, Fallbrook, Bonsall, Pala-Pauma Valley, Valley Center, and Hidden Valley. The increased density can be seen when comparing the existing housing density to the 2035 housing density, as shown in Figures 4.13-2 and 4.13-8, respectively. Areas of increased residential density by 2035 would be apparent in some coastal cities such as Oceanside and Encinitas, and City of San Diego coastal communities. Also increased density would occur in more inland areas along the I-8 corridor through Mission Valley, College Area, and into the City of La Mesa, as well as eastern Chula Vista along the SR 125 corridor. In the northern portion of the region, land use changes to accommodate growth in 2035 in the form of spaced rural residential development would occur along the I-15 corridor north of Escondido toward the northern county line and in more eastern areas along I-8, SR 67, SR 78, and SR 94. The SR 78 corridor, from Escondido to I-5, would experience growth and resulting land use density increases of both residential and commercial/office. As shown in Figure 4.11-4, single-family residential development would increase substantially along this corridor as well as additional commercial and industrial growth. The majority of this growth would be centered around the cities of Vista, San Marcos, and Escondido. The pattern of more dense growth along this segment of the SR 78 corridor is also apparent when comparing the existing housing density to 2035 housing density (see Figures 4.13.2 and 4.13-8 in Section 4.13, Population and Housing) and existing employment density to 2035 employment density (see Figures 4.13-3 and 4.13-9). By 2035, some regional growth would be accommodated in the more eastern, rural areas of the region. Development in these areas would be centered mostly along highway corridors, such as SR 78, SR 67, I-8 east of El Cajon, and SR 94, and generally within San Diego County community planning areas. The unincorporated portions of San Diego County are currently undergoing population growth and expansion of residential land use as indicated by a population increase of 14 percent from 2000 to 2010 as shown in Table 4.11-2. When comparing the existing land uses and 2035 land uses in Figures 4.11-1 and 4.11-4, the 2035 land use pattern would generally involve additional residential development in areas that were previously undeveloped open space or at some time in agricultural use (as discussed in Section 4.2). As discussed in the 2020 analysis, development associated with the 2050 RTP/SCS could expose people and property to seiche, tsunami, and mudflow. However, based on the above analysis and compliance with the regulations outlined above, people or structures would not be exposed to a significant risk of inundation due to seiche, tsunami, or mudflow.



Transportation Network Improvements

Some key highway improvements in place by 2035 would include continued widening along portions of I-5; additional HOV and Managed Lanes along portions of I-5, I-15, I-805, and SR 52; widening of portions of SR 125 and SR 67; and additional freeway and HOV connector improvements. Some important transit projects operational by 2035 would include continued increases in COASTER service, increases in SPRINTER service, increases in downtown area streetcar service, and substantial increases in rapid bus service throughout the region. The Trolley Blue Line would be extended from UTC to Mira Mesa via Sorrento Mesa and Carroll Canyon; the Orange Line would be extended to Lindbergh Field; Phase 1 of the new Mid-City to Downtown San Diego line would provide service from the Mid-City transit station via El Cajon Boulevard to Downtown; and a new line from Pacific Beach to El Cajon via Kearny Mesa, Mission Valley, and San Diego State University would be established. Double-tracking along the SPRINTER rail line through the cities of Oceanside, Vista, San Marco, and Escondido would take place by 2035 as well as continued double-tracking along the LOSSAN corridor. As discussed in the 2020 analysis, the transportation network improvements that are planned for the region by 2035 could be exposed to impacts from seiches, tsunamis, and mudflows. However, based on the above analysis and compliance with the regulations outlined above, people or structures would not be exposed to a significant risk of inundation due to seiche, tsunami, or mudflow. Conclusion

For 2035, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not expose people or structures to a significant risk of inundation due to seiche, tsunami, or mudflow. Therefore, this impact is less than significant. 2050


By 2050, the population of the region is forecast to increase by 1,160,435 people; housing by 379,664 units; and employment by 501,958 jobs over existing conditions. As shown in Figure 4.11-5, new growth and land use changes in 2050 per the 2050 RTP/SCS are apparent throughout the region. Areas of substantial land use change and development, beyond that described in 2035 would include significant industrial development in the County’s Otay planning area and San Diego Otay Mesa community surrounding the East Otay Mesa POE; throughout County planning areas located along the international border including Tecate, Potrero, Campo/Lake Morena, Boulevard, and Jacumba; throughout the Ramona and Julian planning areas in the unincorporated County; throughout other northeastern County planning areas, including North Mountain, Desert, and Borrego Springs; and continued development throughout County planning areas located north and east of Escondido extending to the northern border with Riverside County, including Rainbow, Fallbrook, Bonsall, Pala-Pauma Valley, Valley Center, Hidden Valley, Twin Oaks Valley, and North County Metro. Increased population density from 2010 through 2050 can be seen when comparing Figures 4.13-1, and 4.13-10, respectively. Increased density is most apparent in City of San Diego communities near the downtown area near I-5 and I-805 and along the I-8 corridor to the east. Urban centers in the western third of the San Diego region would have most available land developed with single- and multi-family uses, commercial and office uses, and industrial uses. Consistent with the goals of the 2050 RTP/SCS, the dense growth within existing urban centers with high accessibility to transit options allows for the creation of communities that are more sustainable, walkable, transit-



oriented, and compact. Substantial dense growth within the urban centers corresponds with major transportation corridors such as I-5, I-8, I-15, and I-805 and these are also alignments that would have extensive transit opportunities. Similar to the description in the 2035 analysis, growth would continue in more eastern locations of the region, such as east of I-15 in the northern area, east of SR 67 through the middle portion of the region, and east of SR 94 in the southern area. However, by 2050, spaced rural residential development would have expanded beyond areas along existing transportation corridors and established rural communities and into areas with very minimal development at present. As shown in Figure 4.11-5, some of these areas include northeast of Escondido to SR 76, areas east of Camp Pendleton, and areas north and south of the SR 78 corridor. As shown in Figure 4.11-5, by 2050, a substantial pocket of industrial development would be located along the planned SR 905 corridor in conjunction with the new Otay Mesa East POE at the international border with Mexico. This is a newly developing area that is planned for mainly industrial use and is highly dependent upon the planned construction of SR 11, SR 905, and the Otay Mesa East POE. As discussed in the 2020 and 2035 analyses, development associated with the 2050 RTP/SCS could expose people and property to seiche, tsunami, and mudflow. However, based on the above analysis and compliance with the regulations outlined above, people or structures would not be exposed to a significant risk of inundation due to seiche, tsunami, or mudflow. Transportation Network Improvements

Transportation improvements planned for 2050 are located throughout the western half of the San Diego region, but unlike the improvements planned by 2020 and 2035, several of these planned improvements extend into the less populated areas at the edge of the highly urbanized areas. By 2050, most of the highway, transit, and active transportation (bicycle and pedestrian) improvements, along with other infrastructure projects, would be in place and operational in accordance with the proposed 2050 RTP/SCS. Some key highway improvements that would be in place by 2050 would include widening portions of SR 52, SR 56, SR 76, SR 94, SR 125, and I-5; additional HOV lanes and Managed Lanes along segments of I-805, I-5, I-15, SR 94, SR 125, and SR 54; and freeway and HOV connector improvements. Important transit improvements in place by 2050 would include the extension of Trolley lines and increased Trolley service frequency. The Trolley Green Line would be extended to Downtown-Bayside; a new Phase 2 of the line connecting San Diego State University to Downtown San Diego tovia El Cajon Boulevard/Mid-City would be constructedextended to San Diego State University; and a line from University Town Center to San Ysidro Palomar Trolley Station in the South Bay via Kearny Mesa, Mission Valley, Mid-City, and National City, and Chula Vista would be established. As discussed in the 2020 and 2035 analyses, the transportation network improvements that are planned for the region by 2050 could be exposed to impacts from seiches, tsunamis, and mudflows. However, based on the above analysis and compliance with the regulations outlined above, people or structures would not be exposed to a significant risk of inundation due to seiche, tsunami, or mudflow. Conclusion

For 2050, compliance with existing regulatory requirements described above and in Section 4.10.2 would ensure that the 2050 RTP/SCS growth/land use changes and transportation network improvements would not expose people or structures to a significant risk of inundation due to seiche, tsunami, or mudflow. Therefore, this impact is less than significant.



4.10.5 MITIGATION MEASURES

The following mitigation measures aim to reduce impacts related to hydrology and water quality. These mitigation measures are general and programmatic in nature, and would be refined in project-specific CEQA documents. WQ-2 DRAINAGE PATTERN ALTERATIONS

2020, 2035, 2050

Implementation of the 2050 RTP/SCS would result in significant impacts to drainage areas (WQ-2) in 2020, 2035, and 2050. Implementation of Mitigation Measure WQ-A would reduce impacts to a level that is less than significant. WQ-A During project-specific design and CEQA review, SANDAG shall and other

implementing agencies can and should develop detailed erosion control mitigation measures tailored to the project and site to be developed and included in the SWPPP upon application for a Construction General Permit. During construction, implementing agencies can and should avoid construction on unstable slopes and erosion-prone areas where possible; use special construction techniques to minimize erosion; and manage on-site grading to maximize the capture and retention of on-site runoff by creating perimeter ditches, trenches, siltation ponds, or similar depressions. Low-impact development (LID) guidance provided by the Governor’s Office of Planning and Research (http://www.opr.ca.gov/ceqa/pdfs/Technical_Advisory_LID.pdf) as well as other implementing agencies such as the County’s LID Handbook shall be used to select Low-impact development (LID) design features. These features, including drought-tolerant landscaping, shall be incorporated into each drainage design to the maximum extent practicable. Where permanent, postconstruction BMPs are specified (e.g., detention/retention systems), features shall be utilized for temporary sediment trap devices during construction. In addition, agencies can and should develop an erosion control and revegetation plan for the project site to delineate measures to minimize soil loss and prevent short-term and long-term significant soil erosion problems. Routine site inspections should be made to assess long-term effectiveness of soil erosion control.

4.10.6 SIGNIFICANCE AFTER MITIGATION

WQ-2 DRAINAGE PATTERN ALTERATIONS

2020, 2035, 2050

Implementation of the 2050 RTP/SCS would result in significant impacts to drainage patterns. Implementation of Mitigation Measure WQ-A would reduce impacts to a less than significant level through the incorporation of LID design features and by requiring a detailed erosion and water runoff mitigation plan specific to each project that would be included in the SWPPP, with an objective of minimizing impacts to drainage areas. Responsible agencies would be encouraged to conduct the following:

• Identify and avoid areas with unstable slopes and local factors that can cause slope instability (groundwater conditions, precipitation, seismic activity, slope angles, and geologic structure).



• Develop a site grading and management plan to identify areas of disturbance; areas of cut and fill; slope during and after grading; existing vegetation; and measures to protect slope, drainages, and existing vegetation in the project area.

• Identify and avoid areas with unstable slopes and local factors that can cause slope instability (groundwater conditions, precipitation, seismic activity, slope angles, and geologic structure).

• Develop an erosion control and revegetation plan to delineate measures to minimize soil loss and reduce sedimentation to protect water quality.

• Use special construction techniques in areas of steep slopes, erodible soils, and stream crossings.

• Conduct routine site inspections to assess the effectiveness of and the maintenance requirements for erosion and sediment control systems.

This mitigation measure would be included in project-level planning, design, and analysis, as appropriate CEQA reviews. Implementation of this mitigation measure would require project implementation agencies to follow comprehensive, proven procedures to assess the magnitude of impact anticipated on a project level, and avoid or substantially reduce soil erosion and related impacts. Therefore, with implementation of this mitigation measure, impacts to drainage patterns would be less than significant.

4.10 HYDROLOGY AND WATER QUALITY · 2011. 10. 18. · 4.10 Hydrology and Water Quality SANDAG 2050...

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