<P> The Ogallala Aquifer is a shallow water table aquifer surrounded by sand , silt , clay and gravel located beneath the Great Plains in the United States . One of the world 's largest aquifers , it underlies an area of approximately 174,000 sq mi ( 450,000 km ) in portions of eight states ( South Dakota , Nebraska , Wyoming , Colorado , Kansas , Oklahoma , New Mexico , and Texas ) . It was named in 1898 by geologist N.H. Darton from its type locality near the town of Ogallala , Nebraska . The aquifer is part of the High Plains Aquifer System , and rests on the Ogallala Formation , which is the principal geologic unit underlying 80 % of the High Plains . </P>
what states have access to the ogallala aquifer
South Dakota Nebraska Wyoming Colorado Kansas Oklahoma New Mexico Texas