million gallons per day; however, the annual usage of the RRWA water system is equal to only 4 inches of Rathbun Lake water surface. References Sources U.S. Army Corps of Engineers: Rathbun Lake – Dam and River Basin U.S. Army Corps of Engineers: Rathbun Lake – Lake Facts U.S. Army Corps of Engineers: Rathbun Lake – Recreation Opportunities Midwest Sailing Rathbun Yacht Club Iowa Department of Natural Resources KCRG-TV News – Honey Creek State Park Resort Open for Business Honey Creek Resort State Park Rathbun Regional Water Association Reservoirs in Iowa Bodies of water of Appanoose County, Iowa Tourist attractions in Appanoose County, Iowa Dams in Iowa United States Army Corps of Engineers dams