On November 25, 1950, heavy rains raised the upper Genesee River and severe flooding inundated upstream towns and villages, with many families rescued by boat and town roads and the state highway under water, but although Mount Morris Dam was not yet complete, it prevented flood damages downstream. Mount Morris Dam weighs 1,600,000 tons, about the equivalent of 320,000 full-grown adult elephants. More than 400 people worked on the dam during its four-year construction period, and two men died in work-related incidents. At the base of the dam, nine tunnel-like conduits carry water from the upstream side to the downstream side and control river flow. Operations staff monitor weather conditions and reports in Pennsylvania and New York to decide how many conduits to open or close. When fully open, each conduit is 5 feet wide by 7 feet high, large enough for a small vehicle such as a Volkswagen Beetle to drive through. Typically, 3 to 3.5 conduits remain open during dry weather, 1 to 2 during rain and high water, and in large storms like Hurricane Agnes in 1972, all gates are closed to hold water behind the dam.
