Oklahoma Water Facts

Groundwater

• Oklahoma is underlain by 23 major groundwater basins containing 320 million acre-feet of water in storage, though only one-half of that amount may be recoverable. Groundwater is the prevalent source of water in the western half of the state.
• The state's largest groundwater basin, the Ogallala Aquifer in western Oklahoma, contains 86.6 million acre-feet of supply--enough to cover the entire state two feet deep.

Surface Water

• Oklahoma has approximately 11,611 miles of shoreline, slightly less than the estimated combined general (nontidal) coastline of the Atlantic, Gulf, Pacific, and Arctic Coasts (12,383 miles).
• Oklahoma has approximately 78,578 miles of rivers/streams (about three times the circumference of the Earth and one-third the distance to the moon.)
• Oklahoma's longest river is the Beaver/North Canadian River (766 miles); the Red River is the second longest (592 miles).
• Oklahoma contains approximately 1,120 square miles of water area in its lakes and ponds.
• Oklahoma's largest lake in surface area is Eufaula (105,000 acres); Lake Texoma is second (88,000 acres). The state's largest lake in conservation storage is Texoma (2.6 million acre-feet of water); Eufaula is second (2.3 million acre-feet).
• Average annual lake evaporation in Oklahoma ranges from 48 inches in the extreme east to 65 inches in the southwest, numbers that far exceed the average yearly rainfall in those areas.

Water Use

• Irrigation is the number one use of water in Oklahoma; water supply is a close second, followed distantly by livestock watering.
• Groundwater accounts for almost 90 percent of total irrigation water use in Oklahoma.
• The majority of the state's surface water (approximately 60 percent) is used for public water supply, followed by thermoelectric power generation and irrigation.
• Evaporation and percolation preclude immediate use of approximately 80 percent of Oklahoma stream water.
• The approximate number of stream water permits on file at the OWRB is 2,600; the approximate total allocated stream water use in Oklahoma is 2.6 million ac-ft/year.
• The approximate number of groundwater permits on file at the OWRB is 10,000; the approximate total allocated groundwater use in Oklahoma is 3.2 million ac-ft/year.
• An estimated 34 million acre-feet of water flows out of the state each year through Oklahoma's two major river basins, the Red and Arkansas.

Flooding

• Almost half of flood-related deaths occur in vehicles, primarily when people drive into flooded highway dips or low-drainage areas at night.
• There are approximately 40,000 structures in Oklahoma that reside within the boundaries of the regulatory floodplain, yet less than 10,000 of these are covered by flood insurance.

Rainfall

• One inch of rain falling on a 160 acre field delivers 4,344,680 gallons of water, or 13.3 acre feet. It would take just over 4 miles of 80,000 gallon capacity railroad tank cars to transport this amount of water, which would weigh more than 18,000 tons.