The Pawcatuck River
By Alan Desbonnet and Karen Schneider
The Pawcatuck River and its estuary create a natural border between portions of southern Connecticut and Rhode Island. The glacially formed Pawcatuck River watershed spans an area of 317 square miles260 square miles in Rhode Island and 57 square miles in Connecticut. This watershed is Rhode Island's largest, draining nearly one third of the state. It stretches approximately 23 miles north to south, 20 miles east to west, and discharges an average of 675 cubic feet per second of freshwater into the estuary at Westerly, R.I. The Usquepaug, Wood, and Ashaway rivers are the major tributaries of the Pawcatuck.
The freshwater drainage basin runs through rural uplands, woodlands, forests, and small towns that were once thriving mill villages. While scattered industries can be found along the river, large industrial complexes are somewhat isolated from its banks. In the estuary (the saltwater portion of the watershed), rural land use gives way to the urban center of Pawcatuck-Westerly, R.I. Industry is historically more common in this section of the watershed, due to the proximity of the ocean and overland shipping to New York, Providence, and Boston.
Little Narragansett Bay, at the southern extent of the watershed, is shallow and provides protected waters for recreational boaters and a barrier beach at Napatree Point that is used extensively by summer beach-goers. Little Narragansett Bay also provides a high-quality ecological habitat for a variety of birds, fishes, invertebrates, marine plants, and occasional marine mammals, such as harbor seals.
The first known users of the Pawcatuck River were the Native American Indian tribes of Niantic, Pequot, and Narragansett, who hunted and fished throughout the extensive watershed. Although resident Indian tribes relied heavily on the natural resources of the watershed, their uses did not significantly alter the landscape characteristics of the watershed. European colonists soon exploited the protected waters of the estuary; and by 1680, shipbuilding was the most active occupation along the banks of the river, converting forest and marsh to commercial and residential uses. Shipbuilding proliferated into the 1800s when the Industrial Revolution shifted the attention of regional investors to industrial manufacturing. The river's naturally flowing waters provided a source of power for factories, and industrial development of the watershed began.
The first mills, powered by water, ground grains for flour and meal with little harmful effect on the watershed. With the adoption of textile processing in nearby Providence, these gristmills were converted to wool and cotton processing, which produced wastewater that was discharged directly into the river. The largest textile processing factory, the White Rock Company, was founded in 1814 along the Pawcatuck River in the White Rock region of Westerly.
As textile mills flourished throughout the watershed, a series of dams were constructed along the Pawcatuck to harness waterpower for factories. With the growth of industry, river damming continued into the mid-1900s. Unfortunately, this practice ultimately led to the extinction of the Atlantic salmon population in the river by denying access to adult salmon returning upriver to spawn. As more factories appeared along the river and estuary, the growing demand for a work force drew more people into the region. As both the number of mills and people within the watershed increased, so did the extent and volume of industrial and municipal wastes discharged into the river, resulting in poor water quality. Increased pollution of the river continued into the 1950s, when the textile industry in New England abruptly collapsed and many of the region's factories closed. Many of the abandoned factories fell to ruin, but others were converted to new industrial uses.
Improvement of water quality conditions in the river and estuary began when the textile industry collapsed, reducing the volume of wastewater entering the river, and continued with the construction of sewage treatment facilities in Westerly and Pawcatuck. However, planned control and abatement of pollutant discharges did not begin in earnest until passage of the Clean Water Act in 1972. With adoption of this act, standards for wastewater discharge from industrial and municipal plants were instituted and water quality improved.
Current Water Quality
Water quality in the Pawcatuck River watershed has steadily improved over the past decade as more stringent pollutant discharge regulations were adopted. In addition, the development of new technology allows for better treatment of wastewater prior to its discharge. Although the windrows of visible garbage, textile processing dyes, and floating sewage are no longer seen, the waters of the Pawcatuck River retain a tea-brown coloration. The coloration of the water is often mistaken for water pollution but is, instead, a natural product of the breakdown of leaves and organic material from the heavily wooded regions of the watershed.
Recent studies conducted by several teams of University of Rhode Island researchers, in cooperation with the R.I. Department of Environmental Management, have shown that the water in both the river and the estuary is generally of high quality, and provides healthy habitat for a wide variety of plants and animals.
Concentrations of metals, such as lead, copper, zinc, and nickel, have decreased over the past decade in waters entering the estuary from the Pawcatuck River. These metals generally were not found in concentrations considered to be harmful to aquatic life, according to U.S. Environmental Protection Agency standards.
Nutrients, such as nitrogen and phosphorus, are abundant in the river and estuary. Runoff from fertilized agricultural and residential areas, sewage treatment facilities, and septic systems add nutrients to rivers, streams, and groundwater throughout the watershed. One effect of excess nutrients is algal blooms and fish kills, but there is no evidence to suggest that the estuarine portion of the watershed has, or is, suffering similar symptoms. A heavy growth of "fouling" organisms on the blades of eelgrass in Little Narragansett Bay has been suggested to be the result of excess nitrogen in the estuary, but further study is required to determine if the level of nutrients in the river and estuary is affecting aquatic life.
Concentrations of bacteria measured in the river and estuary are high enough to prohibit use of shellfish resources in both the river and Little Narragansett Bay, which has been closed to shellfishing since 1947. But over the past few years, bacterial concentrations have improved to the point where shellfishing has been allowed in Rhode Island and/or Connecticut waters on a conditional basis since 1990. As bacterial sources are identified and controlled in the estuary, shellfish resources will become more consistently available to recreational users of both states in the future.
The Future of the Pawcatuck
Improvements in water quality in the Pawcatuck River and its estuary show that pollution control and management procedures in the watershed are having a positive effect. An interstate management plan for the Pawcatuck River estuary has been formulated by Connecticut and Rhode Island state representatives, and adoption of the plan was completed in 1992. The plan provides for cooperative planning and use of the estuary between the two states. State borders are disregarded in order to manage the estuary as a united system rather than as separate state entities. Long-term water quality monitoring is presently conducted only in the freshwater portion of the Pawcatuck River watershed. Planned expansion of monitoring to the estuary will aid in evaluating changes in water quality resulting from adherence to the management plan, and will provide greater understanding of the interaction between watershed and estuary.
Implementation of the management plan will begin a new era for the estuary, one that will include interstate plans for the wise use of natural resources and provide protection for the many ecologically significant regions of the estuary. Future management efforts will need to forge a link between the watershed and the estuary in order to achieve management in an ecosystem basis.
For more information, see Pawcatuck Watershed Water Resources: A Management Issues Profile. (pdf)
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