NRCS and the Northern Rhode Island Conservation District identified the Scituate Reservoir watershed as not having a watershed assessment in place that addresses agriculture. This watershed plan assesses water quality conditions related to agriculture to determine voluntary conservation efforts.
Rhode Island NRCS funded an NWQI watershed assessment for the 39 square mile Scituate Reservoir watershed (HUC -12: 010900040606) in Providence County, north-central Rhode Island. This watershed assessment aims to fulfill requirements needed to enter the implementation phase of the National Water Quality Initiative (NWQI).
Background
The Scituate Reservoir watershed lies within the broader Narraganset Bay Basin. Water flows into the Scituate Reservoir from five smaller tributary reservoirs (Barden, Moswansicut, Ponaganset, Regulating, and Westconnaug) and an extensive network of rivers and smaller streams. The Pawtuxet River discharges from the Scituate Reservoir at its southern tip.
The Y-shaped reservoir is nearly six miles long with an average depth of 32 feet and a maximum depth of 90 feet just upstream of the Gainer Dam. The total area draining to the reservoir covers about 94 square miles (9% of the total area of Rhode Island).
The reservoir can store almost 37 billion gallons of water and is the primary potable water supply for Rhode Island, supplying drinking water to more than 60% of the state's residents and businesses. The reservoir is owned and managed by the Providence Water Supply Board (PWSB) and serves the city of Providence, the surrounding metropolitan area, and eight public water suppliers. The average demand for treated water is approximately 61 million gallons per day.
The watershed area is approximately 75% forested. Agricultural land makes about 2% of the area and is distributed throughout the watershed. Most agricultural operations are small backyard farms, with agricultural land predominantly dedicated to forage (e.g., other hay/non-alfalfa, pasture). Developed land makes up 8% of the area.
Water Quality Degradation Resource Concerns and Impairments
Occasional high levels of nutrients (nitrogen and phosphorus) and bacteria are the main water quality concerns for the Scituate Reservoir watershed. Parts of the Westconnaug Brook and Wilbur Hollow Brook are impaired due to excessive levels of bacteria (Enterococcus). No Total Maximum Daily Load (TMDL), however, has been approved. Recent U.S. Geological Survey (USGS) and PWSB water quality monitoring data also indicates elevated levels of nutrients occurring episodically at stream sites throughout the watershed.
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Additional Information
National Water Quality Initiative - Rhode Island
As USDA’s premiere water quality initiative, National Water Quality Initiative (NWQI) provides a way to accelerate voluntary, on-farm conservation investments and focused water quality monitoring and assessment resources where they can deliver the greatest benefits for clean water.
Learn MoreWatershed Planning in Rhode Island
We all live in a watershed. Watersheds provide a vital resource for all living things to survive and thrive. All watersheds are interconnected, creating a land-water system that conveys water to its final destination such as a river, lake, wetland, or bay.
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