The largest fresh waterbody in Rhode Island, the Scituate Reservoir is the source of Providence Water’s supply. The Y-shaped reservoir is nearly 6 miles long and has a storage capacity of nearly 37 billion gallons at the Gainer Dam spillway elevation. Its average depth is about 32 feet, while it reaches a depth of 90 feet just upstream of the dam.

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. In total, Providence Water owns surface reservoirs covering about 5,000 acres and another 13,000 acres of surrounding forestland.