After passing through Allegany County communities like Wellsville and Houghton, the Genesee River flows north through Letchworth State Park and the City of Rochester before emptying into Lake Ontario. The hydropower it provided was essential in the beginnings of Rochester’s heavy industry. Fortunately, the Mount Morris Dam, built twenty years before the flood, protected Rochester. Without the dam, it is estimated that the river would have risen twenty feet in Rochester. Instead, the city only had to contend with three inches of rain.
Other areas were less lucky. Around Dansville, the Canaseraga Creek spilled over its protective levees and flooded the surrounding farmland. Draining the fields took most of the summer.
In total, Hurricane Agnes did millions of dollars of damage to crops and farmland as topsoil was washed away. Contemporary reports stated that huge areas of farmland dedicated to potatoes and corn between Elmira and Bath had been destroyed.
Mount Morris Dam. Courtesy of Stilfehler on Wikimedia Commons.
This immense dam was built after the Flood Control Act of 1944. The Genesee River Valley had suffered severe flooding, on average, every seven years before this dam was built.
Water is at the base of the spillway. Courtesy of Don Gibson, Norma Gibson, Tom Cook & Tom Breslin of Letchworth Park History.
When the water reached the top of the dam in 1972, sluices were opened to lower the level. It is estimated that the $25 million dam saved the city of Rochester $210 million in damage (equivalent to $1.4 billion in 2022).