Indian Rock Dam is an earth and rock structure 1,000 feet long rising 83 feet above the streambed, with a side-channel spillway and gated outlet conduit in the right abutment. The normally dry reservoir area has a storage capacity of 28,000 acre-feet (9.1 billion gallons) at spillway crest and controls a drainage area of 94 square miles, equivalent to 41 percent of the watershed upstream from York. The Codorus Creek project consists chiefly of 22,969 feet of channel improvement including channel widening and deepening, flood walls, levees, protection of bank slopes, and removal of a mill dam which increased channel capacity to 24,000 cubic feet per second. The two components protect the community against flood discharges about 33 percent greater than the record flood of August 1933. Tropical storm Agnes (June 1972) filled the flood control reservoir and produced spillway flow.
The project contributes to Executive Order 13508 goals to protect habitat and water quality within the Chesapeake Bay watershed. The project is operational and recreation is not available.
Location: The protective works for York, Pa., consist of Indian Rock Dam, which is located about three miles upstream from York, and channel improvements on Codorus Creek in the city.
Authorization: The project was authorized by the Flood Control Act of June 22, 1936, as amended by the Flood Control Act of June 28, 1938, and is described in House Document No. 702, 77th Congress, second session.