POPULATIONDraft – April 2017

1. OVERVIEW

Historically (1850–1900), population grew four-fold in the watersheds of urban Providence and Fall River during the industrial Industrial revolutionRevolution. More recently, from 2000 to 2010, the entire Narragansett Bay watershed’s population increased by nearly 8 percent to 1.95 million people. Importantly, this recent population growth was concentrated in suburban and lesser-developed areas, while population showed a slight decline in the historically urbanized coastal subwatersheds. Because population growth typically leads to increased nutrient loading, more impervious surfaces, habitat fragmentation, and other stressors, population trends, especially when considered from a geospatial perspective, are an important indicator of stressors on the Narragansett Bay watershed.

2. INTRODUCTION

It is well established that the way human society uses and protects the land within a watershed has critical implications for freshwater streams, estuarine waters, and associated habitats. Human population growth is one of the fundamental driving forces in land conversion, bringing increases in infrastructure, transportation, and commerce (Meyer and Turner 1992, August et al. 2002). Human populations are often concentrated in coastal regions for economic and recreational resources, and population density can have direct effects such as altering runoff patterns, decreasing the amount of habitat, and introducing exotic species (Niemi et al. 2007). Higher population densities are associated with higher percentages of impervious surfaces and infrastructure, such as water and sewer lines, utility corridors, and roads, all of which influence the natural movement of water and directly contribute to point and nonpoint pollution. The Narragansett Bay Estuary Program uses population density as an indicator of watershed stressors and to spatially track development pressures.

To examine changes in land use in relation to population density, one can calculate the amount of developed land per capita (Tu et al. 2006). This metric indicates the extent and rate of sprawl, a term used to describe the spread of development into rural or undeveloped areas when despite population levels staying level or even declinedeclining. Urban areas with high population density generally have low amounts of developed land per capita, as people in urbanized areas tend to occupy less developed land. Conversely, rural or suburban areas may have lower population density but a higher amount of developed land per capita, meaning that each person

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effectively occupies more developed land than in urban areas (Tu et al. 2006).

Between 1850 and 1900, the population of the entire Narragansett Bay watershed more than tripled (Table 1; Vadeboncoueur et al. 2010). Most of the population growth during that period was concentrated in the coastal areas of the upper Bay, including Providence and Fall River, where population quadrupled (Table 1). Between 1900 and 2000, the population in the Bay’s watershed more than doubled.

Table 1. Historical rates of population growth in the entire Narragansett Bay watershed and in watersheds within it (Vandeboncoueur et al. 2010)

Industrialization Suburbanization Century

Watershed 1850–1900

1900–1950 1950–2000 1900–

2000Blackstone River above Millville 3.4 1.8 1.1 2.0Blackstone R. Millville to Manville 2.3 1.8 1.2 2.1Pawtuxet R. above Pettaconsett 1.4 1.6 3.4 5.4Taunton R. above Bridgewater 2.9 1.5 2.0 3.1Taunton R. Bridgewater to Taunton 2.7 1.3 1.6 2.1Taunton R. below Taunton 1.4 2.2 2.8 6.2Small watersheds 4.1 2.0 1.6 3.1Upper Bay 4.0 1.6 1.0 1.6Lower Bay 1.9 2.1 1.6 3.5Narragansett Bay (entire watershed) 3.2 1.7 1.4 2.3

Between 1850 and 1950, the subwatersheds with the highest percentages of the Bay watershed’s total population were the upper Bay (ranging between 32 and 40 percent) and the upper Blackstone River (18 to 20 percent) (Table 2; Vadeboncoueur et al. 2010).

Table 2. Historical percentage of population in watersheds of Narragansett Bay (Vandeboncoueur et al. 2010)Watershed 1850 1900 1950

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Blackstone River above Millville 18% 19% 20%Blackstone R. Millville to Manville 6% 5% 5%Pawtuxet R. above Pettaconsett 6% 3% 2%Taunton R. above Bridgewater 12% 10% 9%Taunton R. Bridgewater to Taunton 5% 4% 3%Taunton R. below Taunton 4% 2% 2%Small watersheds 10% 13% 15%Upper Bay 32% 40% 38%Lower Bay 8% 4% 5%Narragansett Bay (entire watershed) 260,

660832,438

1,417,816

Because population growth is linked intrinsically to land use change, weanalyzed spatial patterns of land development over time in relation to population growth. In some parts of the Narragansett Bay watershed, the amount of developed land has increased at a faster rate than the population has grown. The movement of population into rural areas has the greatest potential for increased habitat fragmentation, loss of forested lands, and increases in pavement and other impervious land cover.

3. METHODS

We used theThe United States Census Bureau’s projections for 2014 were used to estimate recent population sizes in the Narragansett Bay watershed (U.S. Census Bureau 2014). Although the last census was completed in 2010, the Census Bureau provides projections of population for subsequent years using a cohort-component method and assumptions about demographic components of change (future trends in births, deaths, and net international migration). U.S. Census block group data for Massachusetts and Rhode Island was were used to calculate the 2014 population using areas weighting models which aggregate data from block groups within the perimeter of the watershed (ESRI 2014). We chose to use tThe 2014 projections were used rather than the now dated 2010 population data.

To analyze temporal and spatial trends in population density across the watershed, a dasymetric mapping technique was used to map population density relative to residential land use and land cover types (Sleeter and Gould 2007, USGS 2015). Dasymetric models and mapping of human population density are geospatial techniques used to increase the spatial resolution of population data by incorporating related ancillary data layers such as land use and land cover (USGS 2015). Tracking spatial trends in population density allows assists in the detection of the phenomenon of sprawl. The dasymetric mapping tool used census data from 1990, 2000, and 2010, and land use data from the 1980s, 1990s, and 2000s (Table 3).

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We used lLand use datasets obtained from Massachusetts and Rhode Island state agencies were used because they provide a finer spatial resolution than the National Land Cover Database, and the years in which the data were collected correspond more closely to the Census Bureau data.

Table 3. Data sources and years used for dasymetric analysisCensus Bureau

YearMassachusetts

(MassGIS) Rhode Island (RIGIS)1990 MA 1985 RI 19882000 MA 1999 RI 2003–042010 MA 2005 RI 2011

Dasymetric total population estimates were determined for each state, clipped to watershed boundaries, and then summarized for the Narragansett Bay watershed, as well as for the HUC10 watersheds and HUC12 subwatersheds (USGS 2017) within the Narragansett Bay watershed. The analysis included a calculation of the net percentage change in population.

To evaluate how land use across the watershed has changed and to measure the extent of sprawl, we calculated the amount of developed land per capita, using the dasymetric total population estimates and data on urban land use (Vogelmann et al. 2001, Homer et al. 2007, Homer et al. 2015). This metric was calculated as developed acres of HUC10 watersheds and HUC12 subwatersheds per 100 people. A high value of the metric indicates sprawl.

We used aA kernel density analysis was used to highlight the changes (increases and decreases) in population from 1990 to 2010. Kernel density analysis takes known quantities of some a given phenomenon (e.g., change in population) and spreads them across the landscape based on the quantity that is measured at each location and the spatial relationship of the locations of the measured quantities (ESRI 2014). We generated a heat map using the kernel density tool and the dasymetric population estimates for 1990 and 2010. The 1990 raster was subtracted from the 2010 raster, points were generated from the difference between rasters, and any points in a water body larger than 1 acre were removed (ESRI 2016). Using the remaining points, we created a kernel density raster at a cell size of 100 meters (328 feet), with a search radius of 1,000 meters (3,281 feet).

To estimate past and future housing densities at a finer spatial scale, we analyzed the 2014 population estimates (U.S. Census Bureau 2014) were analyzed using statistical methods developed by researchers at Oregon State University (Silvis 2014). The result is a spatially detailed assessment of housing density derived from decennial census data at partial block group level. State housing density data were combined, the polygons with housing density values of zero and -999 were removed, and area weighting

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was used to estimate the population of the partial block groups.

4. STATUS, TRENDS, AND PROJECTIONS

StatusThe estimated population in the Narragansett Bay watershed based on the 2014 census projections was 1,962,003 people (Table 4). Slightly more than half (51 percent) of the population lived in Massachusetts and 49 percent in Rhode Island. The 2014 estimates were similar to the 2010 census results, based on dasymetric modeling, which estimated a total of 1,949,764 people in the watershed—just over 12,000 fewer than the 2014 projections (Tables 4 and 5). The 2010 census population density (Figure 1), coupled with population of the eleven HUC10 watersheds (Table 5), illustrated the range and distribution of urbanized watersheds (20 percent of the total population) to rural watersheds (2 percent of the total population) (Figure 1).

Table 4. Estimated populations in 2014 of the Massachusetts and Rhode Island sections of the Narragansett Bay watershed and of the entire Bay watershed (U.S. Census Bureau Block Projections)

Estimated Population

Percentage of Bay Watershed

PopulationMassachusetts section of Bay watershed 1,009,890 51%Rhode Island section of Bay watershed 952,113 49%Narragansett Bay Watershed 1,962,003

Table 5. Population in 2010 in watersheds (HUC10) of Narragansett Bay and percentage of the total Bay watershed population. Watersheds are listed from highest to lowest populationHUC10 Watershed (Name)

HUC10 Code Population

Percentage ofBay Watershed

PopulationNarragansett Bay 01090004

09 384,963 20%Upper Blackstone River

0109000301 294,361 15%

Woonasquatucket River-Moshassuck River

0109000405

208,973 11%

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Pawtuxet River 0109000406

208,714 11%

Lower Blackstone River

0109000302

203,717 10%

Upper Taunton River

0109000401

198,325 10%

Lower Taunton River-Frontal Mount Hope Bay

0109000408

159,335 8%

Ten Mile River 0109000404

106,129 5%

Middle Taunton River

0109000402

81,228 4%

Threemile River 0109000403

64,865 3%

Palmer River 0109000407

39,154 2%

Narragansett Bay Watershed 1,949,764

6

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Figure 1. 2010 population density in Narragansett Bay watershed Through analysis of the 2010 census results for the HUC12 subwatersheds, we identified the five subwatersheds with the highest populations and the five with the lowest were identified (Table 6).

Table 6. Subwatersheds (HUC12) with the highest and lowest populations in 2010 HUC12 Subwatersheds Subwatershed Population

(Percentage of Bay Watershed Population) Name Code

Highest population and percentTatnuck Brook-Blackstone River

010900030102

139,119 (7%)

Seekonk River-Providence River

010900040901

125,740 (6%)

Woonasquatucket River 010900040502

125,517 (6%)

Matfield River 010900040102

108,987 (6%)

Ten Mile River 010900040401

106,129 (5%)

Lowest population

Chepachet River 010900030203

5,421 (0.3%)

Scituate Reservoir 010900040606

4,850 (0.2%)

Barden Reservoir-Ponaganset River

010900040605

3,751 (0.2%)

Big River 010900040601

2,586 (0.1%)

Upper West Passage 010900040906

1,946 (0.1%)

TrendsFigure 2 shows historical and recent trends in population in the Narragansett Bay watershed. The data for 1990, 2000, and 2010 are based on dasymetric analysis of census data (Table 7). Historical population trends

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(1850 to 1980) are derived from Vadeboncoueur et al. (2010; Table 1). Figure 2 also shows the percentage change that occurred in each decade. From 1990 to 2010, population increased 141,812 people for a net percentage change of 8 percent (Table 7). The majority of that increase in population (5 percent) occurred between the 1990 and 2000 census.

Table 7. Change in population from 1990 to 2010 in HUC10 watersheds and the entire Narragansett Bay watershed

HUC10 Watersheds

Population Gross ChangeNet % Chang

e1990 2000 2010 1990–

20002000–2010

1990–2010

Middle Taunton River 63,434 73,440 81,228 10,006 7,788 22%Threemile River 51,944 61,263 64,865 9,320 3,602 20%Lower Blackstone River

179,030

193,587

203,717 14,557 10,131 12%

Upper Blackstone River

265,811

276,790

294,361 10,979 17,572 10%

Woonasquatucket River-Moshassuck River

189,104

204,918

208,973 15,814 4,055 9%

Lower Taunton River-Frontal Mount Hope Bay

148,386

159,970

159,335 11,584 -635 7%

Pawtuxet River 195,829

204,065

208,714 8,236 4,649 6%

Palmer River 36,744 38,641 39,154 1,897 513 6%Upper Taunton River

186,402

195,473

198,325 9,071 2,851 6%

Ten Mile River 99,922 104,984

106,129 5,062 1,145 6%

Narragansett Bay 391,345

394,658

384,963 3,313 -9,695 -2%

Narragansett Bay Watershed

1,807,952

1,907,790

1,949,764 99,838 41,974 8%

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Figure 2. Total population in the Narragansett Bay watershed from 1850 to 2010 and percentage change per decade. Line represents total population; bars are decadal percent change.

Of the 52 HUC12 subwatersheds in the Narragansett Bay watershed, 42 had increases in population between 1990 and 2010, and the remaining 10 had decreases. The subwatersheds with the largest net percent increases and decreases are listed in Table 8.

Table 8. Subwatersheds (HUC12) with the largest increases and decreases in population (net percentage change) from 1990 to 2010 HUC12 Subwatersheds Population Net % Change

Name Code 1990 2000 2010199

0–200

0

2000–

2010

1990–

2010

Largest Net % Increases (1990–2010)

West River 010900030201 8,385 10,45

113,56

8 20% 23% 38%

Big River 010900040601 1,815 2,300 2,586 21% 11% 30%

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Cotley River-Taunton River

010900040204

30,064

36,548

40,847 18% 11% 26%

Winnetuxet River-Taunton River

010900040201

11,844

13,767

15,686 14% 12% 24%

Wading River 010900040301

21,105

25,092

27,135 16% 8% 22%

Assonet River 010900040802 6,726 7,997 8,525 16% 6% 21%

Abbott Run 010900030207

19,427

22,246

24,350 13% 9% 20%

Largest Net % Decreases (1990–2010)

Seekonk River-Providence River

010900040901

129,079

129,353

125,740 0.2% -3% -3%

Greenwich Bay 010900040903

46,798

47,363

45,484 1% -4% -3%

Quequechan River 010900040803

51,680

50,918

49,550 -1% -3% -4%

Upper East Passage 010900040907

17,900

17,367

17,077 -3% -2% -5%

Upper Narragansett Bay

010900040902

21,971

21,680

20,748 -1% -4% -6%

Aquidneck Island-Frontal Atlantic Ocean

010900040911

20,094

19,792

18,218 -2% -9% -10%

Lower East Passage 010900040909

25,248

23,546

21,933 -7% -7% -15%

Of the 52 HUC12 subwatersheds, 11 added more than 5,000 people between 1990 and 2010; there largest increase was nearly 15,000 people (Table 9). Conversely, 6 subwatersheds decreased in population by more than 1,000 people. These gains and losses are illustrated in Figure 3.

Table 9. Gross total population change from 1990 to 2010 in HUC12 subwatersheds of the Narragansett Bay watershed

HUC12 Subwatersheds PopulationGross Total

ChangeName Code 1990 2010 2000-

2010 Increased by more than 5,000 people:

Woonasquatucket River 010900040502 110,571

125,517 14,946

Cotley River-Taunton River 010900040204 30,064 40,847 10,783

Quinsigamond River 010900030103 56,249 66,774 10,525

Mill River (Taunton) 010900040801 37,775 45,043 7,268

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Threemile River 010900040302 30,839 37,730 6,891

Tatnuck Brook-Blackstone River 010900030102 132,318

139,119 6,801

Peters River-Blackstone River 010900030208 71,800 78,469 6,669

Ten Mile River 010900040401 99,922

106,129 6,207

Wading River 010900040301 21,105 27,135 6,030

Singletary Brook-Blackstone River 010900030105 31,74

0 37,183 5,443

West River 010900030201 8,385 13,568 5,183Decreased by more than 1,000 people:

Upper Narragansett Bay 010900040902 21,971 20,748 -1,223

Greenwich Bay 010900040903 46,798 45,484 -1,314

Aquidneck Island-Frontal Atlantic Ocean 010900040911 20,09

4 18,218 -1,876

Quequechan River 010900040803 51,680 49,550 -2,130

Lower East Passage 010900040909 25,248 21,933 -3,315

Seekonk River-Providence River 010900040901 129,079

125,740 -3,339

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Figure 3. Heat map of Population population change from 1990 to 2010 in Narragansett Bay subwatersheds (HUC12)

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The amount of developed land per capita is a measure of the development patterns in the HUC10 watersheds (Table 10). Densely populated urban areas have lower amounts of developed land per capita, whereas suburban or rural areas, especially those with sprawl, have higher amounts. The subwatersheds (HUC12) with the highest and lowest amounts of developed land per capita are listed in Table 11.

Table 10. Developed land per capita in 1990, 2000, and 2010 in the HUC10 watersheds of Narragansett Bay. Sorted from highest to lowest values of developed land per capita in 2010.HUC10 Watersheds Developed Acres/100

peopleName Code 1990 2000 2010

Middle Taunton River0109000402 34 38 39

Palmer River0109000407 31 35 38

Threemile River0109000403 30 32 33

Lower Blackstone River0109000302 21 24 26

Lower Taunton River-Frontal Mount Hope Bay

0109000408 17 19 21

Pawtuxet River0109000406 18 19 21

Narragansett Bay0109000409 18 19 20

Upper Taunton River0109000401 17 19 19

Upper Blackstone River0109000301 16 18 19

Ten Mile River0109000404 17 18 18

Woonasquatucket River-Moshassuck River

0109000405 17 11 12

Narragansett Bay Watershed 18 20 21

Table 11. Subwatersheds (HUC12) with the highest and lowest amounts of developed land per capita between 1990 and 2010. Sorted by 2010 values of developed land per capita.HUC12 Subwatersheds Developed Acres per 100

peopleName Code 1990 2000 2010More than 50 developed acres per 100 people:

Upper West Passage010900040906 112 101 100

Big River010900040601 76 83 82

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Barden Reservoir-Ponaganset River

010900040605 55 57 67

Scituate Reservoir010900040606 43 49 54

Assonet River 010900040802

42 48 54

Winnetuxet River-Taunton River 010900040201

35 45 51

Moswansicut Pond-Huntinghouse Brook

010900040604

41 46 51

Less than 15 developed acres per 100 people:Pawtuxet River 0109000406

0913 14 14

Matfield River 010900040102

12 13 14

Quequechan River010900040803 10 11 13

Woonasquatucket River010900040502 12 11 12

Moshassuck River010900040501 11 11 11

Tatnuck Brook-Blackstone River010900030102 11 11 11

Seekonk River-Providence River010900040901 10 10 10

Projections of Housing DensityThe number of household units per square kilometer (km) in the Narragansett Bay watershed increased by a factor of 1.6 between 1940 to 2000, and projections for 2030 suggest that household density will be almost double that of 1940 (Table 12) (Silvis 2014). Figure 4 illustrates patterns of development by comparing estimated household densities in 1940, 2010, and 2030.

Table 12. Estimated and projected household density in the Narragansett Bay watershed (Silvis 2014)

Number of household units per square km1940 1970 2000 2030

Narragansett Bay Watershed 570 754 914 1,030

Past (1940)Household Density

Recent (2010)Household Density

Future (2030)Household Density

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Figure 4. Estimated and projected household density in the Narragansett Bay watershed Watershed (Silvis 2014).

The projections of household density between 2010 and 2030 (Silvis 2014) were analyzed at the municipal scale to identify the towns and cities expected to increase the most, increase the least, or decline (Table 13). In addition, household density projections for 2030 were calculated for the largest cities and towns in the watershed (Table 14).

Table 13. Municipalities in the Narragansett Bay watershed projected to have the highest and lowest increases, or declines, in household density (percent change) between 2010 and 2030Municipalities within theNarragansett Bay Watershed1

Household Density(Household units/sq.km)

Projected Percent Change in

Household DensityTown/City State 2010 2030 2010–2030

Highest projected increasesin household density

Berkley MA 97 126 23%Douglas MA 63 79 21%Uxbridge MA 104 131 20%Bridgewater MA 184 230 20%Upton MA 107 133 19%East Bridgewater MA 140 173 19%Halifax MA 105 129 19%

Lowest projected increasesin household density

Cranston RI 1,150 1,200 4%Somerset MA 385 402 4%Pawtucket RI 1,989 2,060 3%Woonsocket RI 1,369 1,413 3%Fall River MA 2,269 2,317 2%Jamestown RI 187 190 1%

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Projected declinesin household density

Middletown2 RI 578 556 -4%Newport2 RI 1,160 1,068 -9%Portsmouth2 RI 985 904 -9%1 Municipalities that are completely within the watershed or >60% within the watershed. 2Aquidneck Island is home to these three towns.

Table 14. Municipalities in the Narragansett Bay watershed with the greatest projected household densities and their projected percent change between 2010 and 2030. Sorted by highest projected household density.

Town/City State

Projected Household Density in 2030

(Household units/sq.km)

Projected Percent Change in Household

DensityProvidence RI 2,429 5%Fall River MA 2,317 2%Central Falls RI 2,255 5%Pawtucket RI 2,060 3%Worcester MA 1,756 6%Woonsocket RI 1,413 3%Brockton MA 1,272 11%Cranston RI 1,200 4%North Providence RI 1,164 7%Newport RI 1,068 -9%

5. DISCUSSION

Population growth is an important indicator of underlying pressure on?? and a driver of many related stressors (see the chapters in this volume on land use, impervious cover, nutrient loading, and wastewater infrastructure). Within the Narragansett Bay watershed, trends in population growth can be analyzed back to the 1850s (Figure 2). New geospatial demographic methods such as dasymetric modeling and mapping allow for spatial enhancement of the U.S. Census Bureau data, providing improved trend analyses in population growth across the Narragansett Bay watershed.

The historic centers of urban and industrial development (Providence, Worcester, and Fall River) continue to dominate as population centers (Figure 1); however, development patterns from 1990 to 2010 show losses in these urban cores, especially Providence and Fall River, and gains in adjacent suburban areas (Figure 3). Projections through 2030 for growth in household density illustrate continued growth, or sprawl, in these adjacent areas (Figure 4). Unless effective management practices are implemented

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as populated areas expand, these trends will likely have a direct impact on the Narragansett Bay watershed, changing physical conditions including water clarity and quality, dissolved oxygen concentrations, and water quality, biological parameters such as chlorophyll, and human health through beach and shellfishing closures.

The watershed with the largest population was coastal Narragansett Bay HUC10, which includes Providence and much of Fall River, with 384,963 people. In 19XX?, it accounted for 20 percent of the entire Narragansett Bay watershed’s population (Table 4; Figure 1). At the subwatershed (HUC12) scale, the largest population was concentrated in Worcester (Tatnuck Brook-Blackstone River subwatershed) with 139,119 people (Table 6). In coastal areas of Narragansett Bay, the Seekonk River-Providence River and Woonasquatucket River subwatersheds also were heavily populated (Table 6). The least-populated HUC12 subwatersheds included the Upper West Passage, which encompasses the industrial areas of Quonset Point and the sparsely populated western portion of Prudence Island, the Big River, the Barden and Scituate Reservoirs, and the Chepachet River (Table 6).

In recent trends between 1990 and 2000, the HUC10 watersheds that experienced the largest increases in gross population included the Upper and Lower Blackstone River and the Woonasquatucket River-Moshassuck River (Table 7). The largest net percentage increases in population from 1990 to 2010 occurred in the Middle Taunton River (22 percent) and Threemile River (20 percent) (Table 7). The only HUC10 watershed with a loss in population was the coastal Narragansett Bay HUC10, which includes the lands directly adjacent to and entirely surrounding Narragansett Bay, where population declined 2 percent (Table 7). Within that watershed, the loss of population can be seen in more detail at the subwatershed (HUC12) scale. Two subwatersheds on Aquidneck Island had the greatest net percent decreases in population at -10 percent and -15 percent (Table 8). The Seekonk River-Providence River subwatershed had the largest decline of gross population of 3,339 people (-3 percent net change) (Table 9).

Among all the subwatersheds (HUC12) around Narragansett Bay, the largest net percent increases in population between 1990 and 2010 occurred in the West River (38 percent) and Big River (30 percent) subwatersheds (Table 8; Figure 3). The geospatial kernel (Figure 3) shows the areas with the largest gross population increases and declines. The largest population increase at the HUC 12 scale was in the Woonasquatucket River subwatershed, where a total of 14,947 people moved into its suburban areas. The second-largest increase occurred in the Cotley River-Taunton River subwatershed, where population increased by 10,782 (Table 9). The increases in the Taunton River Basin can be seen in Taunton and Bridgewater in Figure 3.

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The HUC10 watersheds with the largest amounts of developed land per capita were the Middle Taunton River and the Palmer River watersheds, which in 2010 had nearly 40 acres of developed land per 100 people (Table 10). In contrast, the Woonasquatucket River-Moshassuck River subwatershed had only 12 acres of developed land per 100 people (Table 10). At the subwatershed (HUC12) scale, the Upper West Passage in 2010 had nearly 100 acres of developed land per 100 people, or approximately 1 acre per person, and it consistently had the highest amount among all subwatersheds from 1990 to 2010 (Table 11). The densely populated Seekonk River-Providence River subwatershed had only 10 acres of developed land per 100 people, or 0.1 acre per person (Table 11).

Looking to the future, the municipal-level analysis revealed seven municipalities, all in Massachusetts, where the household density is projected to increase by 2030 to levels approximately 20 percent higher than 2010 levels (Table 13; Figure 4). Towns with the smallest projected increases in household density by 2030 are Jamestown (1 percent) and Fall River (2 percent) (Table 13). Declines in household density are projected for three towns—Newport, Middletown, Portsmouth collectively known as —located on Aquidneck Island (Table 13). Urban areas in the Narragansett Bay watershed are projected to continue having the greatest household densities, averaging between 1,068 and 2,429 household units per square kilometer in those municipalities by 2030 (Table 14).

Population and associated development are increasing in the lesser-developed areas of the Narragansett Bay watershed. To protect the environmental quality of the watershed, effective land use management and regional planning practices must be implemented. As future Census Bureau reports become available, the geospatial analyses conducted here will be updated and trend monitoring continued to inform land use and planning decisions at local and watershed scales.

6. DATA GAPS AND RESEARCH NEEDS

There are no critical data gaps or research needs, assuming that detailed U.S. census data continue to be collected each decade and that funds are made available to conduct geospatial analyses. A needed next step is to examine the status and trends for population in the Southwest Coastal Ponds and Little Narragansett Bay watersheds. This will provide a more comprehensive analysis of trends as well as provide context for other indicators, e.g., (list some of the more important ones relative to these areas). More robust data analyses should be performed to interrelate total population changes with developed area per capita and housing density, two factors that are linked to the effects of population driving changes in the watershed.

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7. ACKNOWLEDGEMENTS

This chapter was written by Eivy Monroy (Watershed and GIS Specialist with the Narragansett Bay Estuary Program), Anne Kuhn (U.S. Environmental Protection Agency, Office of Research and Development, Atlantic Ecology Division, Narragansett RI), and Michael Charpentier (GIS Analyst with SRA International, Inc., A CSRA Company). Assistance in the development of this chapter was provided by Peter August (University of Rhode Island, Department of Natural Resources Science) and Paul Jordan (Rhode Island Department of Environmental Management). The information in this document has been subjected to Environmental Protection Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

8. REFERENCES

August, P., L. Iverson, and J. Nugranad. 2002. Human Conversion of Terrestrial Habitats. In: Applying Landscape Ecology in Biological Conservation, K.J. Gutzwiller (Ed.). Springer, New York. 518 pp.

U.S. Environmental Protection Agency (EPA). 2015. Report on the Environment: Urbanization and Population Change. U.S. Environmental Protection Agency, Washington, D.C. Available at: https://cfpub.epa.gov/roe/indicator.cfm?i=52

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