Mansfield Hollow Lake Dam lies on the confluence of the Natchaug, Fenton, and Mt. Hope Rivers, in the township of Mansfield Center, CT. The dam is part of a network of six flood control dams in the Thames River Basin, that were constructed and are maintained by the U.S. Army Corps of Engineers. This network helps to reduce flooding in communities along the Thames River by controlling water on upstream tributaries in Massachusetts and Connecticut.

The Corps regulates the flow of the Natchaug River by raising, or lowering five, 5' X 7' hydraulically operated sluice gates from within the gatehouse at Mansfield Hollow Lake. The water flowing through this gatehouse drains an area of 159 square miles.

Total potential flood control storage at Mansfield Hollow Lake amounts to 16.1 billion gallons of flood water, at a maxium level of 257 feet, mean sea level (m.s.l.). Water stored during potential flooding conditions is released after water levels downstream recede.