Authorization: Flood Control Act (Public Law 81-516a) approved May 17, 1950, Project Document HD 442, 80th Congress, 2d Session.  Public Law 101-253 (S1016) changed the name of Marion Lake, northwest of Marion, Kansas, to Marion Reservoir. 

Location: On the Cottonwood River, a tributary of the Grand (Neosho) River, at river mile 126.7, 3 miles northwest of Marion in Marion County, Kansas, and 46 miles north-northeast of Wichita, Kansas.

Status: Complete.

Purpose: Flood control, water supply, water quality, and recreation.

Associated Structures:  The Saddle Dike has a length of 3,610 ft. (STA. 0+00 to STA. 36+10) and a crest elevation of 1368.0 ft. The Rim Dike as length of 1,115 ft. (STA. 42+35 to STA. 53+50) and a crest elevation of 1368.0 ft.

History of Construction: Construction began in March 1964; embankment closure was completed in October 1967; and the project was placed in full flood control operation in February 1968.

Type of Structure: The rolled earth-filled embankment is 7,983.23 feet long, excluding the concrete spillway and non-overflow sections; rises about 67 feet above the streambed; and has a 24-foot road across the embankment and spillway. Including the spillway structure, the dam stretches from STA. 16+76.77A to STA. 100+80A, with an overall length of 8,403.23 feet.

Spillway & Outlet Works: The spillway is a gate-controlled, concrete-gravity, ogee weir with a gross width of 136 feet. The spillway is located near the right abutment and connects to the embankment with two concrete non-overflow sections 142 feet long. Three 40- by 40-foot tainter gates control flows through the spillway. Maximum discharge is 132,000 cubic feet per second (cfs). Two 24-inch-diameter pipes are located through the left non-overflow section; one for low flow and the other for municipal and industrial water supply connections. Channel capacity of the stream at the dam site is 6,000 cfs.

Hydrologic Data: The release of record occurred in June and July 1951 (preconstruction) with a peak discharge of 54,000 cfs and a volume of 78,950 acre-feet which is equivalent to 7.40 inches of runoff from the drainage area above the dam site.