The Goodnough Dike (actually a dam) is on the southeastern end of the Quabbin Reservoir, the largest water body in Massachusetts. It impounds the waters of Beaver Brook and therefore closes that exit to the Chicopee River Watershed. The Goodnough Dike is not as large as the Winsor Dam, but it is equally important as they both trap the waters of the Quabbin Reservoir. This dam is part of the metropolitan Boston's water supply, maintained by the Massachusetts Water Resources Authority.