Optima Lake, Lake and federal wildlife refuge in Texas County, Oklahoma, US.

Optima Lake is a reservoir in Texas County, Oklahoma, held by an earthen dam 120 feet high and 16,875 feet long at its crest, completed in 1978. The lake has never exceeded five percent of its 618,500 acre-foot capacity and is often dry. Around it lie the Optima National Wildlife Refuge and the Optima Wildlife Management Area.

The dam was completed in 1978 as part of a water management project for the region. The development reflected broader efforts to address agricultural challenges that farmers had faced after the 1930s.

The lake's name comes from the nearby town of Optima, and the site is now used for hunting and wildlife watching. Optima Wildlife Refuge, managed by the U.S. Fish and Wildlife Service, grew from a planned 2,605 acres to 4,334 acres as the lake shrank. The Optima Wildlife Management Area on the Beaver River side expanded to 8,062 acres for hunting.

All public use areas around the lake are land access points only; the Corps states there is no swimming, boating, fishing or camping. The water level has never reached normal pool and the lake is often dry. Picnicking and wildlife viewing are possible in the natural setting, with or without water.

The reservoir was built with major funding but never filled to its intended capacity due to declining water flow from the Beaver River. This makes it an example of the challenges in water storage for this semi-arid landscape.