West Valley is a hamlet in the Town of Ashford in Cattaraugus County, New York, United States. The population was 518 at the 2010 census, which lists the community as a census-designated place. Located at the intersection of Cattaraugus County Route 53 and State Route 240/County Route 32, the hamlet is home to West Valley Central School and the West Valley Demonstration Project, a nuclear cleanup facility.