Keystone Lake was named after the community of Keystone, a post office from 1900-1962. The name stems from the circumstance that the original site, inundated by the waters of the lake, was in a key position at the Junction of the Cimarron and Arkansas Rivers. The former town sites of Mannford, Prue, Appalachia, and part of Osage also were abandoned because they were in the lake area.

Mannford, which took its name from Mann's Ford across the Cimarron River adjoining the town site, was relocated southward and Prue northward out of reach of the lake water. At Cleveland, established shortly after the opening of the Cherokee Strip in 1893, the Corps of Engineers protected low-lying areas with a levee that rims the south and east sides of the city. In the old days the Triangle Country - the land between the Arkansas and the Cimarron - was full of wild game such as buffalo, deer, bear and turkey. The Osage Reservation was to the north, bordered by the Arkansas River, and the Creek Reservation lay just to the south.

A major American explorer made a journey up the Arkansas River from Fort Smith and into the valley of the Cimarron River in the spring of 1819. He was Thomas Nuttall, a professor of botany at Harvard, who studied the plants and flowers of the region. Washington Irving, noted American writer, and his companion, John Joseph Latrobe, an English traveler who wrote "The Rambler in North America," visited the country around Keystone Dam in 1832. They accompanied a detachment of Rangers, mounted infantry from Fort Gibson on a tour of exploration of the western wilderness. In his book, "A Tour on the Prairies," Irving wrote of their overnight camp in Bear's Glen about one mile north of the Keystone Dam. Camp Arbuckle was established in 1834 near the Junction of the Cimarron and Arkansas Rivers. It was one of three outposts established to protect the Leavenworth Expedition that set out in June 1834 for the Wichita Mountains. The object of the expedition was to stop a war that had broken out between Osage and smaller tribes of Plains Indians.

Many other famous names are associated with the Keystone area. Captain Nathaniel Boone, son of Daniel, led troops through here on their way to the High Plains in 1843. A famous lawman, U S Marshall Nix, chased outlaws into the area's hills and caves.

HISTORY AND DEVELOPMENT The project was authorized by the Flood Control Act of 1950. It was designed by the Tulsa District, U S Army Corps of Engineers, and built under supervision of the Corps. Construction of the dam began in December 1956 and was completed for flood control operation in September 1964. Commercial operation of the Keystone power plant in the production of electrical energy began in the spring of 1968. A re-regulating dam about 7 miles downstream from the dam was completed in 1968. Cost of overall construction was approximately $123 million.