Land Development Patterns in the Narragansett Bay Watershed
October 22, 2008Land uses are among the most important, if not the most important, drivers affecting water quality, water quantity, and habitat.
The landscape of the Narragansett Bay watershed has evolved through four centuries of economic change, yet for most of that time, has managed to maintain its characteristic pattern of distinct urban centers surrounded by rural settlements. But in the last 40 years, that pattern has become increasingly blurred by sprawl development. Between 1970 and 1995, Rhode Island’s developed land increased by 43 percent, even as population increased by 10 percent and households shrank to an average of 2.47 persons (RI Statewide Planning, 2006). And since the last R.I. Statewide Planning comprehensive inventory in 1995, even more undeveloped land has been built on; in some high activity communities in Rhode Island’s South County, the percentage is as high as 70 percent. Southeastern Massachusetts, with 60 percent of the Narragansett Bay watershed, has experienced similar patterns particularly in those areas consider commuter communities. The result has been a redistribution of population and accompanying utilities, housing, transportation, and jobs.
In the Bay watershed, each wave of land uses has left a legacy for good or ill on the land and in the Bay. Farming cleared forests, creating the beautiful rural landscapes so prized today, but also eroding the soil and destroying woodland habitats. Dammed rivers generated power that fueled an explosion of industrial activity, but in the process altered riparian habitats and doomed the passage of anadromous fish; that same industrial activity spurred enormous economic growth, but poured out toxic pollutants in the water, leaving accumulations of contaminated sediments in many waterways.
The Bay watershed covers a variety of land forms from low-lying coastal plains to hilly and forested headwater lands, reaching up into Massachusetts. Several rivers and many streams run downhill to estuarine waters. Densely settled cities straddle rivers from the top of the watershed to the Bay – Worcester, Taunton, Woonsocket, Pawtucket, Cranston, Warwick, East Providence and Providence. Lands in the watershed have returned to a forested state after serving as agricultural fields for a couple of centuries but those forests have been reduced in recent decades due to the conversion of undeveloped land to residential and commercial uses.
The evolution of prevailing technologies and economies is mirrored in evolving patterns of land use, changing as the societies that create them change. Historically, agriculture was the dominant land use with population nodes in the cities and the remainder of the population scattered about the rural countryside and small villages. As manufacturing replaced agriculture, Rhode Island and Massachusetts residents and waves of immigrants surged into the cities and towns that hosted the new industry, primarily along river systems that provided both power and transportation access. Textile mills, metalworking, and jewelry manufacture were the economic engines of the time, and their legacy is found in the hundreds of abandoned mill buildings, small dams, and industrial facilities lining the watershed’s rivers.
Since World War II, the economy has moved increasingly away from industries that generate significant pollution and towards a mix of service industries, specialized and niche businesses, high technology, and jobs that depend on high levels of environmental quality such as tourism and recreation. The enterprises of this new economy don’t come with the dirty smokestacks and effluent pipes we remember from the past. Instead, we find them near highway interchanges or in malls, office parks, and new subdivisions, drawn by public investments in utilities and roads. Social and environmental impacts derive from the effect of unplanned or inappropriate land uses and nonpoint pollutants generated from thousands of lawns, construction sites, parking lots, and roads.
Land Development Trends
What happens in the Bay watershed is virtually synonymous with Rhode Island statewide trends; only four of Rhode Island’s thirty-nine cities and towns are located totally outside of the watershed of Narragansett Bay; another 55 communities exist in the Massachusetts section of the watershed. The story of their changing landscapes tells not of dramatic population growth but rather of significant population migration into new areas. Since 1970, Rhode Island’s population growth rate has been almost flat, even as land consumption has accelerated dramatically.
According to the Land Use 2025 report by the R.I. Statewide Planning Program, nearly 60% of the state is forested. In the time period 1970-1995, land in residential use has increased by 55% and commercial land has nearly doubled. Industrial land use has increased by 72% and the amount of land used for transportation has increased. The state’s population continues a migration to rural and coastal areas and employment centers have expanded away from central cities. However, since 1995, older cities and suburbs have increased development of vacant land through rehabilitation and reuse. Since 1995, 30% of land designated as undeveloped has been developed. If land development trends continue, by 2025, 45% of the state will be developed and by 2060, 71%.
This pattern is remarkably similar in Massachusetts. Trends tracked by the regional planning programs in Massachusetts mirror those of Rhode Island. Since the 1970s, population growth in the watershed area has been essentially flat, yet land consumption has accelerated dramatically. In southeastern Massachusetts, the amount of developed land is increasing at a rate of 4.1 % a year to accommodate a population growth of 1.6 %. One-third of that area’s open space and agricultural lands have been lost over the past thirty years. In the past thirty years, the populations of the region’s three largest cities have increased by only 3.6 %, but the rest of the region has seen population grow by 80.9 % (Woods Hole Research Ctr., 2007). Adding to the growth pressure on Massachusetts watershed communities, one billion dollars in new transportation improvements are scheduled for construction (rail line extensions and expansion projects for Rte. 44, Rte. 3, and Rte. 24)
Since 1971, about 40% of agricultural lands in southeastern Massachusetts have been lost while residential, commercial and industrial lands have increased by 60% (Woods Hole Research Ctr., 2007). The Woods Hole study projects that, if the current rate of development prevails, developed land in southeast Massachusetts with increase from 29% to 63% by 2030.
The most striking result of land development patterns that we have adopted has been the emergence of nonpoint source pollution as the primary threat. In the past, water quality was predominantly affected by industrial uses. Waterbodies were affected by withdrawals for manufacturing processes and dams for water power, and then used for industrial wastewater and sewage discharges. But today, most of those point sources are controlled, and new obstructions are limited. Instead, the most negative ecological effects come from the day to day activities of people traveling to work, taking care of their lawns and pets, and building places to live. These impacts are stressors to the natural systems that support the ecological and economic health of the watershed.
Massachusetts Watersheds
The Blackstone and Taunton River watersheds make up the majority of the Bay watershed in Massachusetts. Land use impacts incurred up in the Massachusetts part of the watershed are felt in the lower R.I. section and in Narragansett Bay especially in terms on nutrient loading. Both states have been engaged in reducing nutrient loads and the U.S. EPA has recently issued a permit for the Worcester treatment plant which discharges into the Blackstone with more stringent nitrogen and phosphorus limits.
The Blackstone River, with a watershed of about 1300 acres and 29 communities (Blackstone River Coalition, 2008), currently has 63.3% of its watershed land in forest; 8.1% in agriculture; and 17.6% in urban land area. At the head of the Blackstone River is the city of Worcester with a 2007 population of 173,966 – a 0.9% increase since 2000. Although at one time an industrial center with steel works and other heavy industries (some located directly on the Blackstone), the city is now surrounded by residential, commercial and lighter industrial areas.
Taunton River watershed is the second largest in the Commonwealth of Massachusetts. It has an area of 530 square miles and includes 38 towns and 117 subwatersheds. The watershed population in 2003 was estimated at 700,000. Over the last 25 years, land has been developed at a rate of 2.5 times the rate of regional population growth. Percentages of current land uses are: forested - 55.9%; residential and commercial – 27 %; open land – 11.7%; water – 3.3%; and wet land – 2.7%. Over the last 3 decades, residential, commercial, and industrial uses have increased by 55.4%; forested lands have decreased by 12.6%; and wet lands have decreased by 5.2%. (Sekar, et al, 2006)
While the Blackstone and Taunton Rivers are the largest Bay watershed areas in Massachusetts, other watersheds that drain to the Bay are the Ten Mile, Palmer, Runnins, and Lee’s Rivers as well as coastal areas adjacent to Mount Hope Bay. Though they are smaller watersheds, they drain both urbanized and agricultural areas and can have an effect on Bay water quality.