The High Plains aquifer system
underlies 174,000 square miles in parts of eight States (CO, KS, NE, NM,
OK, SD, TX, and WY) (figure 1).
Approximately 20 percent of the irrigated land in the
United States is in the High Plains and about 30 percent of the ground water
used for irrigation in the U.S. is pumped from the High Plains aquifer.
Irrigation withdrawals in 1990 were greater than 14 billion gallons per day. In 1990,
2.2 million people were supplied by ground water from the High Plains aquifer
with total public-supply withdrawals of 332 million gallons per day.
The quality of water in the High Plains aquifer generally is suitable for irrigation use but, in many places, the water does not meet U.S. Environmental Protection Agency drinking-water standards with respect to several dissolved constituents (dissolved solids/salinity, flouride, chloride, and sulfate). Only sparsley scattered water-quality data (except Texas) are available for pesticides, volatile organic compounds, and trace metals in the High Plains aquifer system. Nutrient data are available, to a varying degree, across the aquifer.
Beginning in 1999 and continuing for a period of 6 years, the High Plains Regional Ground Water Study will intensively investigate the quality of ground-water resources within the study area. Investigations will begin in the Central High Plains and move to the Southern High Plains and Northern High Plains as the project progresses (figure 2). The first and most areally extensive component of the intensive study phase is the "Occurrence and Distribution Assessment." The goal of this assessment is to characterize, in a nationally consistent manner, the broad-scale geographic variations of ground-water quality related to major contaminant sources and background conditions.
