Staff Report

CARB Review of the Imperial County

2017 State Implementation Plan for the 2008 8-Hour Ozone Standard

Release Date: September 22, 2017

Hearing Date: October 26, 2017

Electronic copies of this report are online at http://www.arb.ca.gov/planning/sip/planarea/imperial/imperialsip.htm. Alternatively, paper copies may be obtained from the Visitors and Environmental Services Center of the California Air Resources Board, located at 1001 I Street, Sacramento, California 95814, or by contacting CARB’s Office of Communications at (916) 322-2990. For individuals with sensory disabilities, this document is available in Braille, large print, audiocassette, or compact disc. Please contact CARB’s Disability Coordinator at (916) 323-4916 by voice or through the California Relay Services at 711 to place your request for disability services. If you are a person with limited English and would like to request interpreter services, please contact CARB’s Bilingual Manager at (916) 323-7053. This document has been prepared by the staff of the California Air Resources Board. Publication does not signify that the contents reflect the views and policies of the California Air Resources Board, nor do trade names or commercial products constitute endorsement or recommendation for use. For questions, contact: Ariel Fideldy, Air Pollution Specialist South Coast Air Quality Planning Section California Air Resources Board P.O. Box 2815 Sacramento, CA 95812 Phone: (916) 324-8622 Email: ariel.fideldy@arb.ca.gov Or Carol Sutkus, Manager South Coast Air Quality Planning Section California Air Resources Board P.O. Box 2815 Sacramento, CA 95812 Phone: (916) 322-1229 Email: carol.sutkus@arb.ca.gov

Table of Contents EXECUTIVE SUMMARY……………………………………………………………………….1 I. BACKGROUND ...................................................................................................... 2

II. NATURE OF THE OZONE PROBLEM IN IMPERIAL COUNTY ............................. 3

III. DEMONSTRATING ATTAINMENT UNDER SECTION 179B ................................. 6

IV. CONTROL STRATEGY .......................................................................................... 8

V. CLEAN AIR ACT REQUIREMENTS ....................................................................... 9

VI. ENVIRONMENTAL IMPACTS .............................................................................. 13

VII. STAFF RECOMMENDATION ............................................................................... 14 APP. A. SUPPLEMENTAL WEIGHT OF EVIDENCE ANALYSIS………………………A-1

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EXECUTIVE SUMMARY This report presents the California Air Resources Board (CARB or Board) staff’s assessment of the 2017 State Implementation Plan for the 2008 8-Hour Ozone Standard (Ozone Plan) developed by the Imperial County Air Pollution Control District (District) and adopted by the District on September 12, 2017. CARB staff has concluded that the Ozone Plan in combination with this staff report meet the State Implementation Plan (SIP) requirements of the federal Clean Air Act (Act). The Board is scheduled to consider the Ozone Plan on October 26, 2017. If adopted, CARB will submit the Ozone Plan to the U.S. Environmental Protection Agency (U.S. EPA) as a revision to the California SIP. The Act requires U.S. EPA to set air quality standards and periodically review the latest health research to ensure that standards remain protective of public health. Based on research demonstrating adverse health effects at lower exposure levels, U.S. EPA has set a series of increasingly health protective ozone standards, beginning with a 1-hour ozone standard in 1979. Subsequent health studies demonstrated the greater effects of exposure to ozone over longer time periods, resulting in U.S. EPA establishing an 8-hour ozone standard of 80 parts per billion (ppb) in 1997, and the 75 ppb standard in 2008. On May 21, 2012, U.S. EPA designated Imperial County as a Marginal nonattainment area for the 75 ppb 8-hour ozone standard, requiring attainment by 2014. Despite air quality progress, the region did not meet the attainment deadline. On June 3, 2016, U.S. EPA classified Imperial County as a Moderate nonattainment area, which requires the District to submit a SIP meeting Moderate area requirements and attain by July 20, 2018. Over the past twenty years, ozone levels in Imperial County have shown significant improvement in response to emission reductions in both reactive organic gases (ROG) and oxides of nitrogen (NOx). As a result of comprehensive control programs that have reduced NOx emissions 50 percent over the last decade, Imperial County is making steady progress in reducing 8-hour ozone levels. Since 1996, 8-hour ozone concentrations have decreased more than 25 percent. Monitors located in the more-northern cities of Niland and Westmorland now meet the standard, consistently recording values that are well below the standard. The Calexico and El Centro monitors, located approximately one and nine miles, respectively, of the international border with Mexico, remain above the standard. The Act includes a provision under section 179B that allows consideration of the impacts of transport of pollutants across international borders. Section 179B of the Act waives certain planning requirements if it is shown that in the absence of international transport, an area would have attained the standard. Exceedances that occur due to international transport of pollutants may cause violations of the standard; however, the Act does not require states to develop an attainment strategy addressing pollution that originates from sources beyond the United States’ borders. The Ozone Plan utilizes this provision and demonstrates that emissions in Imperial County are at a level

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sufficient to attain the 75 ppb 8-hour ozone standard absent the impact of emissions from Mexico. Importantly, while section 179B provides relief from some planning requirements for nonattainment areas impacted by pollutant transport, it does not obviate the need for those areas to control emissions within their jurisdiction where it is technologically and economically reasonable. To the extent applicable, nonattainment areas impacted by cross-border emissions are required to develop plans that meet all applicable SIP requirements, including the implementation of reasonable control measures. These planning requirements ensure that local emissions are controlled despite any impact foreign emission sources may have on the area. I. BACKGROUND Ozone is a highly reactive gas that can damage the tissues of the respiratory tract, causing inflammation and irritation, and resulting in symptoms such as coughing, chest tightness and worsening of asthma symptoms. Ozone exposure can also lead to decreased lung function. The Act requires U.S. EPA to set air quality standards and periodically review the latest health research to ensure that standards remain protective of public health. Based on research demonstrating adverse health effects at lower exposure levels, U.S. EPA has set a series of increasingly health protective ozone standards, beginning with a 1-hour ozone standard in 1979. Subsequent health studies demonstrated the greater effects of exposure to ozone over longer time periods, resulting in U.S. EPA establishing an 8-hour ozone standard of 80 ppb in 1997, and the 75 ppb standard in 2008, and more recently, the 70 ppb standard in 2015. Effective July 20, 20121, U.S. EPA designated Imperial County as a Marginal nonattainment area for the 75 ppb 8-hour ozone standard. Marginal areas were required to attain the 75 ppb standard by July 20, 2015. Despite air quality progress, the region did not meet this attainment deadline. Consequently, on June 3, 2016, U.S. EPA classified Imperial County as a Moderate nonattainment area requiring the District to submit a SIP meeting Moderate area requirements with an attainment date of July 20, 2018.2 On September 12, 2017, the District adopted the Ozone Plan addressing the requirements of the Act applicable to a Moderate 8-hour ozone nonattainment area under section 179B, consistent with U.S. EPA’s 2015 Implementation Rule for the 2008 8-hour ozone standard (Implementation Rule).3 The Ozone Plan demonstrates that the area would attain the 75 ppb 8-hour ozone standard by 2017 absent the impact of emissions from Mexico. 1 77 FR 3088 http://www.gpo.gov/fdsys/pkg/FR-2012-05-21/pdf/2012-11618.pdf 2 81 FR 26697; https://www.regulations.gov/document?D=EPA-HQ-OAR-2015-0468-0042 3 80 FR 12264 http://www.gpo.gov/fdsys/pkg/FR-2015-03-06/pdf/2015-04012.pdf

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II. NATURE OF THE OZONE PROBLEM IN IMPERIAL COUNTY The Imperial County ozone nonattainment area is located on the border of the United States and Mexico and is adjacent to Riverside County to the north, San Diego County to the west, and the state of Arizona to the east. It encompasses all of Imperial County. The topography, climate, and emission sources in Imperial County and Mexicali provide a starting point in evaluating the transport of pollutants in Imperial County and across the U.S.–Mexico border. Imperial County’s hot, dry weather conditions during the summer cause poor air dispersion and stagnation, which are conducive to ozone formation. As shown in Figure 1, the southern portion of the county and specifically the cities of Calexico and El Centro are close to Mexicali, Mexico. The proximity to Mexicali, a metropolis with five times the area and a population nearly 20 times larger than Calexico, supports the proposition that attainment of the ozone standard in the Imperial County is impeded by emissions emanating from Mexicali. The highest ozone concentrations in the county are consistently measured at the two monitors nearest the U.S.-Mexico border, Calexico and El Centro.

Figure 1. Map of Imperial County and Monitoring Stations

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The Imperial Valley, which extends southward into the Mexicali Valley, is part of the Salton sink geological depression and is bordered by the Peninsular Ranges and the Chocolate Mountain Range to the west and east, respectively. South of the border, the Sierra de los Cucapas Mountains lie to the southwest of Mexicali. These ranges channel airflow within the Imperial and Mexicali Valley facilitating the transfer of pollutants across the international border. The topography, coupled with common meteorology throughout the area, results in a single binational air shed for the region. The Salton sink geologic depression is an expansive area averaging approximately 70 feet below sea level. Mountain valleys often enhance the formation of atmospheric temperature inversions and result in little or no mixing of trapped pollutants. This phenomenon is common in the Imperial Valley, particularly near the border during nights with light winds. The flat terrain of the valley and the strong temperature differentials created by intense solar heating, produce moderate wind and deep thermal convection. The climate of Imperial County is hot and arid with an average of about 3 inches of rainfall per year. Summers are extremely hot with daily average temperature ranges between 104 and 115 degrees Fahrenheit and winds that originate predominately from the southeast. Coastal mountains prevent the intrusion of any cool, damp air found in California coastal environs. In evaluating influences on air quality, the differences between the U.S. and Mexican sides of the international border are most pronounced in terms of magnitude of emission sources. On the U.S. side, within Imperial County, sources of NOx emissions consist primarily of mobile sources with locomotives being the largest contributor; sources of ROG emissions consist primarily of farming operations, with mobile and area sources including burning, being the next largest contributors. Inventory data for the current plan indicate that total emissions of NOx and ROG from the Mexicali Municipality are higher in general than emissions from Imperial County. However, the ability to accurately evaluate and compare inventories is limited due to the lack of information for emission categories in the Mexicali inventory, as well as the overall uncertainty for the emissions estimates provided. The Mexicali Metropolitan Area has a population of over 1 million people as compared to the significantly smaller city of Calexico which has a population of 38,572 people (2010 U.S. Census). Figure 2 shows a nighttime aerial view of Calexico and Mexicali which highlights the large difference in size and population. Because of these differences, the ambient ozone concentrations in Imperial County are adversely impacted by Mexicali emission sources on a regular basis.

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Figure 2. Mexicali and Calexico

Elevated ozone levels occur in Imperial County from May through September, when high temperatures and stable atmospheric conditions favor ozone formation. Ozone generally reaches peak levels by late afternoon and, along with ozone precursors, is often transported by the prevailing winds from Mexicali to the south, and to a lesser extend from the other surrounding air basins. As a result, the southern cities of Calexico and El Centro have higher ozone levels and more days exceeding the federal ozone standard than the County’s more northern areas. Since 1996, 8-hour ozone concentrations in the District have decreased more than 25 percent. Design values are used to demonstrate an area’s ozone compliance status in relation to the standard. The design value is the 4th high, 8-hour ozone value averaged over three years. Imperial County has experienced a reduction in 8-hour ozone design values, as displayed in Figure 3. Over the last 15 years, the site with the highest 8-hour ozone levels has alternated between Calexico and El Centro, the two stations nearest the Mexican border. Since 2000, the County’s 8-hour ozone design value has decreased nearly 20 percent. In 2016, Calexico and El Centro recorded the same design value of 76 ppb, only 1 ppb above the 75 ppb 8-hour ozone standard.

Calexico, CA

Mexicali, Mexico

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Figure 3. 8-Hour Ozone Design Value Trend

Source: CARB iADAM Trends Summaries, https://www.arb.ca.gov/adam/index.html

III. DEMONSTRATING ATTAINMENT UNDER SECTION 179B Section 179B of the Act includes language that reduces planning requirements in international border areas subject to emissions from outside the United States. Specifically, section 179B references requirements for SIPs. In addition to statutory language in the Act, U.S. EPA published guidelines to assist states in the application of section 179B. The guidelines outline five types of information that may be used to substantiate the effect of emissions emanating from outside the United States on a nonattainment area. A state may use one or more of these analytical approaches based on the specific case under evaluation and the availability of data. While U.S. EPA guidance only applies to particulate matter (PM), the concepts are appropriate to use for ozone. Summarized with respect to PM, the five types of information consist of the following:

1. Evaluate and quantify any changes in monitored concentrations with a change in the predominant wind direction;

2. Comprehensively inventory emissions within the United States in the vicinity of the nonattainment area and demonstrate that the impact of those sources on the nonattainment area after application of reasonably available controls does not

0

0.02

0.04

0.06

0.08

0.1

0.12

1996 2001 2006 2011 2016

Ozo

ne (p

pm)

0.075 ppm standard

7

cause the NAAQS to be exceeded. Analysis must include an influx of background PM in the area. Background PM levels could be based, for example, on concentrations measured in a similar nearby area not influenced by emissions from outside the United States;

3. Analyze ambient sample filters for specific types of particles emanating from across the border (although not required, characteristics of emissions from foreign sources may be helpful)

4. Inventory the sources on both sides of the border and compare the magnitude of PM emissions originating within the United States to those emanating from outside the United States

5. Perform air dispersion and/or receptor modeling to quantify the relative impacts on the nonattainment area of sources located within the United States and of foreign sources of PM emissions (this approach combines information collected from the international emission inventory, meteorological stations, ambient monitoring network, and analysis of filters)

As these approaches were written with respect to PM, at least one of them (filter analysis of particle types) does not apply to analyses of ozone. The applicable analyses have been addressed in Appendix I of the Ozone Plan.

Regardless of the applicability of section 179B, all SIPs must identify both the magnitude of reductions needed and the actions necessary to achieve those reductions as part of demonstrating attainment of the standard. CARB and the District have prepared a modeling demonstration that provides for expeditious attainment of the 75 ppb 8-hour ozone standard but for emissions emanating from outside the United States. The demonstration includes the benefits of CARB and District control programs that provide ongoing emission reductions. Continued implementation of these control programs provides new emission reductions each year, resulting in a 17 percent decrease in NOx emissions between 2012 and 2017. The Act and the aforementioned guidance on section 179B require the use of air quality modeling to relate ozone levels to emissions in a region and simulate future air quality based on changes in emissions. CARB staff conducted the modeling for the Ozone Plan. The Imperial County ozone nonattainment area is a small part of the greater Southern California region. The photochemical model used in this plan covers the entire Southern California region and a portion of northern Mexico. The modeled demonstration as applicable under section 179B in the Ozone Plan was prepared using photochemical and meteorological modeling tools meeting U.S. EPA modeling guidelines4, and recommendations from air quality modeling experts. The photochemical model uses emission inventories, with measurements of meteorology and air quality, to establish the relationship between emissions and air quality. The

4 U.S. EPA, 2014, Draft Modeling Guidance for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5 and Regional Haze, available at https://www.epa.gov/ttn/scram/guidance/guide/Draft_O3-PM-RH_Modeling_Guidance-2014.pdf

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modeling is used to quantify the impacts of international emissions on air quality within the District. Results of the attainment demonstration modeling are shown on Table 1. When removing emissions from Mexico, the 2017 design values are predicted to be below the 75 ppb standard at all sites, with values that range between 62 and 68 ppb. Similar to today, the highest concentrations are expected to remain in the southern portion of Imperial County. Further information on the modeled attainment demonstration as applicable under section 179B is included in Chapter 8 and Appendices F, G and H of the Ozone Plan.

Table 1. Modeled 8-hour Ozone Design Values Demonstrating Attainment Absent the Impact from Mexico (ppb)

Site

2012 Base Year Design Value(1)

2017 Future Year Design Value

2017 Future Year Design Value

excluding Mexico Emissions

Niland-English Road 70 67 64 El Centro-9th Street 81 79 68 Calexico-Ethel Street 76 75 62 Source: Ozone Plan, Table 8-2: Baseline Design Value, Modeled RRF, and Projected Future Year (2017 with and

without Mexico Emissions) Design Value for Sites in the Imperial County Federal Nonattainment Area (IFNA) A weight of evidence (WOE) analysis is provided in Chapter 8 of the Ozone Plan, with supplemental information provided in Appendix A to this staff report.

IV. CONTROL STRATEGY The ongoing emission reductions from continued implementation of CARB and District control strategies developed to meet prior standards provide the control strategy for the Ozone Plan. Between 2012 and 2017 in Imperial County, overall NOx emissions will decrease by 17 percent and ROG emissions by 12 percent, as demonstrated in Table 2 in the following section.

A. CARB Control Program Given the severity of California’s air quality challenges, CARB has implemented the most stringent mobile source emissions control program in the nation. CARB’s comprehensive strategy to reduce emissions from mobile sources consists of emissions standards for new vehicles, in-use programs to reduce emissions from existing vehicle and equipment fleets, cleaner fuels, and incentive programs to accelerate market penetration of the cleanest vehicles beyond what is achieved by regulations alone. For example, new passenger vehicle, heavy duty truck, and equipment standards, along with cleaner fuel requirements, adopted over the past two decades have achieved reductions have been important to Imperial County’s improved air quality. A detailed

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description of the mobile source control programs and a comprehensive list of CARB regulations are included in Appendices D and E of the Ozone Plan.

B. District Control Program Consistent with its regulatory authority, the District has adopted rules for reducing emissions from a broad scope of stationary and areawide sources, as detailed in Chapters 6 and 7 and Appendices B and C of the Ozone Plan. These rules apply to many stationary and areawide sources, such as factories, power plants, crude oil storage tanks, boilers, and furnaces. Chapter 8 of the Ozone Plan also includes a discussion of additional District emission reduction programs.

V. CLEAN AIR ACT REQUIREMENTS In addition to the elements related to the attainment demonstration as applicable under section 179B, the Act also requires SIPs for Moderate ozone nonattainment areas to address the following elements:

• Base year emission inventories and future year forecasts for manmade sources of ozone precursors;

• Demonstration that control measures meet the reasonably available control measures (RACM) level;

• Provisions that demonstrate reasonable further progress (RFP); • Provisions for sufficient contingency measures for RFP; • Transportation conformity emission budgets to ensure transportation projects are

consistent with the SIP. A. Emission Inventory

An emissions inventory is a critical tool used to evaluate, control, and mitigate air pollution. At its core, an emissions inventory is a systematic listing of the sources of air pollutants along with the amount of pollutants emitted from each source or category over a given time period. The planning emissions inventory is divided into three major categories: stationary, area-wide, and mobile sources. The summer season inventory is used for ozone planning because it reflects the activity levels and conditions presented when higher ozone levels occur in the Southern California region. The Ozone Plan uses a 2012 base year planning inventory; the inventory was calibrated to 2012 emissions and activity levels, and inventories for other years are backcast or forecast from that base inventory. On-road motor vehicle emissions were generated using CARB’s mobile source emissions model, EMFAC2014. Off-road mobile source emissions were generated using CARB’s OFFROAD model. Both models were

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developed for use in the ozone SIP revisions, and represent significant improvements over models used in prior SIP updates. Forecasted inventories are a projection of the base year inventory that reflects expected growth trends for each source category and emission reductions due to adopted control measures. CARB develops emission forecasts by applying growth and control profiles to the base year inventory. Point-source emissions in the backcast years are the figures reported by Imperial County APCD for those years. Stationary aggregated and areawide emissions for the backcast years are estimated in the same way as the forecast, by applying growth parameters and control profiles to 2012 emissions. All of CARB’s growth parameters and control profiles run back to 2000. Mobile source emissions are estimated in the backcast years with the same models that were used for the forecast years. The forecasted and backcasted inventories reflect values that are derived from the base year emissions; thereby, the 2008 inventory is consistent with the 2012 inventory. As required, the planning inventory year of 2008 is consistent with the baseline year for the Reasonable Further Progress demonstration. Table 2 shows the trends in emissions by source category for 2008, 2012, and 2017, the year modeled to demonstrate attainment for a Moderate classification. Further detail on the Imperial County emissions inventory is provided in Chapter 4 and Appendix A of the Ozone Plan.

Table 2. Imperial County Base Year and Attainment Year Emissions (tpd, summer planning inventory)

Source Category

NOx ROG 2008 2012 2017 2008 2012 2017

Stationary and Area-wide 5 2 2 11 10 9

On-road Mobile 14 10 7 5 4 3

Off-road Mobile 11 9 9 6 5 5

Total 30 22 18 21 19 17 Source: Ozone Plan, Chapter 4.15: Emission Inventories; Numbers may not add up due to rounding

Federal New Source Review (NSR) rules require new and modified major stationary sources that increase emissions in amounts exceeding specified thresholds to provide emission reduction offsets to mitigate the emission growth. Emission reduction offsets represent either on-site emission reductions or the use of banked emission reduction credits (ERC). ERCs are voluntary, surplus emission reductions, which are registered, or banked, with the District for future use as offsets.

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Per U.S. EPA policy, ERCs banked before the plan’s emission inventory base year (2012 for this plan) must be explicitly treated as emissions in the air. As it is known which ERCs are used and which remain to date, Table 3 shows the most recent totals for ERCs registered with the District for future use as offsets. Further detail on ERCs is provided in Chapter 4 of the Ozone Plan.

Table 3. Imperial County Emission Reduction Credits (ERC) Balance as of January 2014 (tpd)

Pollutant ERC Total

NOx 0.56 ROG 0.03

Source: Ozone Plan, Table 4-10: Emission Reduction Credits Added to the Summer Planning Emission Inventories for Imperial County (tons/day)

The Act requires ozone nonattainment areas to have an Emission Statement program that mandates stationary sources with emissions over 25 tons per year of NOx or ROG report and certify the accuracy of NOx and ROG emissions annually. District Rule 116, Emissions Statement and Certification, addresses this requirement as stated in Chapter 10 of the Ozone Plan.

Border Region Emission Inventories The National Emissions Inventory as recently updated for northern Mexico is the most recent, verifiable Mexicali inventory available. The 2012 Imperial County ozone emission inventory was prepared by CARB for the Ozone Plan. A comparison of the two inventories in Table 4 shows the relative magnitude of the emissions in each jurisdiction by major source category. Emissions from sources in the Mexicali Municipal area are significantly higher than in Imperial County for both NOx and ROG. In both Imperial County and Mexicali, a majority of the NOx emissions are from mobile sources and nearly half of ROG emissions are from area-wide sources. For both NOx and ROG though, Mexicali shows significantly higher percentages of emissions coming from stationary sources.

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Table 4. 2012 Summer Imperial County and Mexicali Municipality Emission Inventory (tpd)

Source Imperial County Mexicali Municipality

NOx NOx (%)

ROG ROG (%)

NOx NOx (%)

ROG ROG (%)

Stationary 2 8% 1 7% 15 18% 14 24%

Area-wide 1 3% 9 44% 10 12% 27 46%

On-Road Mobile 10 46% 4 22% 56 66% 17 29%

Other Mobile 9 43% 5 27% 4 4% 0.4 1%

Total 22 100% 19 100% 85 100% 59 100% Source: Ozone Plan, Table 8-1: Imperial County Summer Planning Emissions and the Mexicali Municipality

Emissions within the Modeling Domain for 2012 and 2017; Numbers may not add up due to rounding

B. Reasonably Available Control Measures Demonstration As specified in the Act, the SIP shall provide for the implementation of RACM as expeditiously as practicable to provide for attainment of the ozone standard. RACM must also include emission reductions from existing sources that may be obtained through the adoption, at a minimum, of reasonably available control technology (RACT). The U.S. EPA has interpreted RACM as those emission control measures that are technologically and economically feasible and when considered in aggregate, would advance the attainment date by at least one year. The Ozone Plan contains a RACM demonstration for State, District, and metropolitan transportation agencies that demonstrates no new measures were identified that would affect attainment of the standard given the impact of emissions from Mexico on the area’s attainment status. Further information regarding the RACT analysis can be found in Chapter 6 and Appendix C of the Ozone Plan.

C. Reasonable Further Progress The Act and the Implementation Rule specify that each ozone nonattainment area must demonstrate ongoing emission reductions relative to the RFP baseline year (2008). Federal law requires a three percent per year reduction in ROG emissions. Where both ROG and NOx emissions have been shown to contribute to high ozone levels, the Act allows NOx emission reductions to augment ROG emission reductions in order to demonstrate RFP. Chapter 5 of the Ozone Plan includes an RFP demonstration that meets the Act’s requirements. The analysis indicates that the adopted measures from CARB’s mobile source program will provide emission reductions beyond those needed for Imperial County’s RFP demonstration. As part of the RFP demonstration, the District will rely on a 24 percent reduction of forecasted ROG and NOx emissions (from existing control

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measures) that are projected to occur between 2008 and 2017. Both ROG and NOx emissions are necessary to meet the RFP reduction targets. Imperial County meets the RFP targets in the milestone years of 2014 and 2017 with a 3 percent contingency set aside in 2014 and carried through to 2017.

D. Transportation Conformity Budgets Under section 176(c) of the Act, transportation plans, programs, and projects that receive federal funding or approval must be fully consistent with the SIP before being approved by a Metropolitan Planning Organization (MPO). U.S. EPA’s transportation conformity rule5 details requirements for establishing motor vehicle emission budgets (budgets) in SIPs for the purpose of ensuring the conformity of transportation plans and programs with the SIP. The Ozone Plan establishes county-level on-road motor vehicle emission budgets for the attainment year of 2017. These emission budgets will also apply to all subsequent transportation conformity years, per the federal transportation conformity regulation. Table 5 summarizes the motor vehicle emissions budget for transportation conformity purposes under a Moderate federal 8-hour ozone classification. Emission budgets for NOx and ROG were calculated using EMFAC2014 and reflect summer average emissions. Once U.S. EPA approves the emission budgets established in the Ozone Plan, the budgets will serve as the conformity emissions budgets for future transportation conformity determinations in Imperial County. Additional details on the on-road motor vehicle emission budgets are in Chapter 10 of the Ozone Plan.

Table 5. On-Road Motor Vehicle Emission Budgets (tpd, summer planning inventory)

Pollutant 2017 and Subsequent Years

ROG 4 NOx 7

Source: Ozone Plan, Table 10-1: Transportation Conformity Budgets for the 2008 8-hour Ozone standard in Imperial County

VI. ENVIRONMENTAL IMPACTS The California Environmental Quality Act (CEQA) requires that State and local agency projects be assessed for potential environmental impacts. An air quality plan is a “project” that is potentially subject to CEQA requirements. The District found that the Ozone Plan will not result in any potentially significant adverse effects on the environment and is exempt from CEQA under the provisions of section 15308 (actions

5 Federal transportation conformity regulations are found in 40 CFR Part 51, subpart T – Conformity to State or Federal Implementation Plans of Transportation Plans, Programs, and Projects Developed, Funded or Approved Under Title 23 U.S.C. of the Federal Transit Laws. Part 93, subpart A of this chapter was revised by the U.S. EPA in the August 15, 1997 Federal Register.

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taken by a regulatory agency for protection of the environment) of the CEQA Guidelines. CARB has determined that its review and approval of the Ozone Plan submitted by the District for inclusion in the California State Implementation Plan (SIP) is a ministerial activity by CARB for purposes of CEQA (14 CCR § 15268). A “ministerial” decision is one that involves fixed standards or objective measurements, and the agency has no discretion to shape the activity in response to environmental concerns. (14 CCR § 15369; San Diego Navy Broadway Complex Coalition v. City of San Diego (2010) 185 Cal.App.4th 924, 934.) CARB’s review of the Ozone Plan is limited to determining if it meets all the requirements of the Act. CARB is prohibited from approving it or changing it unless CARB finds that it does not comply with the Act (Health and Safety Code § 41650 and 41652). Since CARB lacks authority to not adopt the plan, or modify it, in response to environmental concerns raised through the CEQA process, CARB’s action on the plan is ministerial for purposes of CEQA.

VII. STAFF RECOMMENDATION CARB staff recommends that the Board:

1. Adopt the Ozone Plan along with this staff report as revisions to the California SIP; and

2. Direct the Executive Officer to submit the Ozone Plan and this staff report to U.S. EPA as a revision to the California SIP.

APPENDIX A

SUPPLEMENTAL WEIGHT OF EVIDENCE ANALYSIS: 2014 – 2016 EXCEEDANCE DAY HYSPLIT ANALYSIS

A-1

2014 – 2016 EXCEEDANCE DAY HYSPLIT ANALYSIS

BACKGROUND The Ozone Plan demonstrates that Imperial County would attain the 75 parts per billion (ppb) 8-hour ozone standard by 2017 absent the impact of emissions from Mexico, thereby demonstrating attainment under Section 179B of the federal Clean Air Act. As discussed in Section III of this staff report, U.S. EPA-published guidance on implementation of Section 179B outlines five types of information that may be used to substantiate the effect of emissions emanating from outside the United States on a nonattainment area. One of these is to evaluate and quantify any changes in monitored concentrations with a change in the predominant wind direction. The District provided an analysis of this type in Appendix I to the Ozone Plan which uses wind roses to show wind directions on exceedance days. This analysis supplements the wind rose analysis using back-trajectories modeled using the National Oceanic and Atmospheric Administration’s (NOAA) Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) for the 6 hours leading up to last hour of each day with a 1-hour average at or above the 75 ppb standard.

SUMMARY This analysis looked at Calexico and El Centro exceedance days for the years 2014, 2015, and 2016. For each exceedance day, the last hour of the day for which the 1-hour averaged ozone value was equal to or greater than 75 ppb was identified. Beginning with that hour, HYSPLIT was used to draw 6-hour back-trajectories for the 6 hours leading up to the latest hour (each line drawn shows the 6-hour back-trajectory for one air parcel data point at the air quality monitor). The analysis shows that a majority of exceedance days at both stations had back-trajectories for at least 4 of the 6 hours drawn which originated from or went through Northern Mexico, indicating influence from sources in Mexicali.

A-2

DATA 1-hour averaged ozone values in ppb

• Red > 75 ppb, Orange = 75 ppb, Green < 75 ppb • Underline + bold = 6-hour back-trajectory originated from or went through Mexico

DATE CALEXICO EL CENTRO

TIME OF DAY

11 am

12 pm

1 pm

2 pm

3 pm

4 pm

5 pm

6 pm

7 pm

10 am

11 am

12 pm

1 pm

2 pm

3 pm

4 pm

5 pm

6 pm

7 pm

4/16/2014 73 74 74 79 90 85 5/16/2014 76 78 87 97 84 78 82 78 79 83 85 91 5/24/2014 69 81 89 92 86 76 5/25/2014 66 74 92 98 93 81 5/26/2014 76 85 96 95 82 77 6/02/2014 64 80 88 96 99 79 6/05/2014 83 82 84 81 80 78 81 85 -- -- 80 80 7/30/2014 78 89 105 92 99 84 4/18/2015 76 81 86 85 81 75 76 79 78 76 91 82 4/19/2015 82 93 92 80 77 75 6/06/2015 79 88 91 90 81 76 71 83 84 82 79 77 6/07/2015 74 83 81 85 85 81 74 79 81 83 88 82 6/08/2015 73 79 77 77 87 80 6/12/2015 62 70 83 85 91 85 9/23/2015 67 80 86 93 87 80 2/29/2016 64 70 79 91 108 93 6/02/2016 58 87 100 96 99 75 7/11/2016 66 71 76 91 89 80 7/12/2016 62 72 87 92 90 78 7/13/2016 71 88 95 86 85 79 Source: NOAA Hybrid Single Particle Lagrangian Integrated Trajectory Model, http://ready.arl.noaa.gov/HYSPLIT.php

A-3

RESULTS Daily maximum 8-hour averaged ozone values in ppb

• Underline + bold = at least 4 out of 6 of the 6-hour back-trajectories from the day originated from or went through Mexico

DATE CALEXICO EL CENTRO

Exceedance Day Max 8-hr Ozone Value

Exceedance Day Values Remaining Excluding

Mexico-influenced Days

Exceedance Day Max 8-hr Ozone Value

Exceedance Day Values Remaining Excluding

Mexico-influenced Days 4/16/2014 76 5/16/2014 80 80 80 5/24/2014 78 5/25/2014 76 5/26/2014 80 6/02/2014 78 6/05/2014 80 80 79 79 7/30/2014 86 86 4/18/2015 77 77 4/19/2015 79 6/06/2015 81 76 6/07/2015 79 78 6/08/2015 76 6/12/2015 77 77 9/23/2015 82 2/29/2016 77 77 6/02/2016 82 7/11/2016 76 76 7/12/2016 77 77 7/13/2016 77

CONCLUSION When excluding days with a likely influence from Mexico, the fourth high in all years 2014, 2015, and 2016 at both stations would be at or below the 75 ppb standard. Therefore, both stations would have a 2016 design value at or below 75 ppb and would be in attainment of the 75 ppb 8-hour ozone standard absent the impact of emissions from Mexico.

YEAR CALEXICO EL CENTRO 4th High 4th High Excluding MX

Influenced Days 4th High 4th High Excluding MX

Influenced Days 2014 78 ≤ 75 78 ≤ 75 2015 77 ≤ 75 77 ≤ 75 2016 74 ≤ 75 74 ≤ 75

A-4

CALEXICO ALL (12 Exceedance Days)

EL CENTRO ALL (13 Exceedance Days)

A-5

CALEXICO 5/16/14: 12pm – 5pm

5/25/14: 1pm – 6pm

6/02/14: 11am – 4pm

A-6

6/5/14: 1pm – 6 pm

7/30/14: 12pm – 5pm

4/18/15: 11am – 4pm

A-7

6/6/15: 2pm – 7pm

6/7/15: 1pm – 6pm

9/23/15: 12pm – 5pm

A-8

7/11/16: 12pm – 5pm

7/12/16: 11am – 4pm

7/13/16: 12pm – 5pm

A-9

EL CENTRO 4/16/14: 12pm – 5pm

5/16/14: 11am – 4pm

5/24/14: 11am – 4pm

A-10

5/26/14: 11am – 4pm

6/5/14: 12pm – 5pm

A-11

4/18/15: 12pm – 5pm

4/19/15: 11am – 4pm

6/6/15: 1pm – 6pm

A-12

6/7/15: 2pm – 7pm

6/8/15: 11am – 4pm

A-13

6/12/15: 10am – 3pm

2/29/16: 12pm – 5pm

6/2/16: 10am – 3pm

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