The Ogallala Aquifer occupies the High Plains of the United States, extending northward from western Texas to South Dakota. The Ogallala is the leading geologic formation in what is known as the High Plains Aquifer System. The entire system underlies about 174,000 square miles throughout eight states.
The Ogallala aquifer is an unconfined aquifer, and nearly all recharge comes from rainwater and snowmelt in certain areas. As the High Plains has a warmer climate, recharge is minimal especially towards the southern part of the aquifer. “Recharge varies by amount of precipitation, soil type, and vegetation cover and averages less than 25 millimeters (1 inch) annually for the region as a whole. In a few areas, recharge from surface water diversions has occurred. Groundwater does flow through the High Plains Aquifer, but at an average rate of only 300 millimeters (12 inches) per day (pubs.water.usgs.gov/fs029-01 - 19k).” “The depth to the water table of the Ogallala Aquifer varies from actual surface discharge to over 150 meters (500 feet). Generally, the aquifer is found from 15 to 90 meters (50 to 300 feet) below the land surface. The saturated thickness also varies greatly. Although the average saturated thickness is about 60 meters (200 feet), it exceeds 300 meters (1,000 feet) in west-central Nebraska and is only one-tenth that in much of western Texas. Because both the saturated thickness and the areal extent of the Ogallala Aquifer is greater in Nebraska, the state accounts for two-thirds of the volume of Ogallala groundwater, followed by Texas and Kansas, each with about 10 percent (pubs.water.usgs.gov/fs029-01 - 19k).” The Ogallala aquifer provides water for residential, industrial, and agricultural use. This large aquifer is mostly used for its widespread of irrigation. Farming accounts for 94 percent of the groundwater use which is needed for the regional economy. “It supports nearly...