Chatfield Dam and Reservoir is a dam and artificial lake located on the South Platte River, south of Littleton, Colorado. The dam and reservoir were built by the United States Army Corps of Engineers as a response to the disastrous flood of 1965. In addition to its primary purpose of flood control, it serves as one of many water supply reservoirs for the city o…Chatfield Dam and Reservoir is a dam and artificial lake located on the South Platte River, south of Littleton, Colorado. The dam and reservoir were built by the United States Army Corps of Engineers as a response to the disastrous flood of 1965. In addition to its primary purpose of flood control, it serves as one of many water supply reservoirs for the city of Denver, Colorado.