Little Falls Dam was built by the U.S. Army Corps of Engineers (COE) in 1959 as a water supply facility for the Washington, D.C. metropolitan area. It is located in Maryland just upriver from the District of Columbia. Since the dam would block upstream fish movement, a vertical slot fishway was built at the same time at Snake Island near the center of the dam. Unfortunately, this fishway never passed migratory fish, mainly because its entrance is too far downstream from the dam, and its maintenance needs were too high due to the large amount of debris carried by the Potomac River. Its operation was abandoned in 1964.
The Maryland Department of Natural Resources (DNR) designated a new fishway at Little Falls Dam as one of its highest priority fish passage projects in 1988. Stimulated by the interest of U.S. Senator Paul Sarbanes, an intergovernmental task group was formed in 1992 to help MD DNR and COE plan and obtain funding for a new fishway at Little Falls Dam. The task group, led by staff from the U.S. Fish & Wildlife Service (FWS), is part of the Chesapeake Bay Program's Fish Passage Workgroup.