High Plains Aquifer Down By 6 Percent

There are some areas on the High Plains where water is being withdrawn from the Oglala aquifer at rates greater than the aquifer is being replenished. In these areas, the aquifer will not be able to sustain withdrawals at current rates in future decades, new research by the U.S. Geological Survey (USGS) has determined.

Underlying portions of eight states, including Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, and Texas, the massive High Plains aquifer, also called the Oglala aquifer, spans 173,000 square miles and provides irrigation and drinking water for one of the major agricultural regions in the world.

But USGS scientists have found a six percent decrease in the volume of water stored in the aquifer from the time groundwater pumping began in the 1940s to the year 2000.

Using data collected by the USGS, other federal, state, and local agencies between the years 1920 and 2000 from more than 20,000 wells screened in the High Plains aquifer, USGS scientists determined that the amount of water stored in the High Plains aquifer has declined about 200 million acre-feet, a decrease of six percent.

The change in storage by state ranges from an increase of about four million acre-feet in Nebraska to a decline of about 124 million acre-feet in Texas.

The two states with the greatest amounts of depletion are Texas and Kansas. Water in storage has declined 27 percent in Texas, from about 476 million acre-feet to 352 million acre-feet over the past 50 years.

In Kansas, water in storage has declined 16 percent from about 322 million acre-feet to 274 million acre-feet during the same time period.

“These declines will have a significant impact on the agricultural economy in the region,” the agency warns.

The High Plains aquifer provides the water to irrigate crops on about 27 percent of the irrigated land in the United States and withdrawals from the aquifer amount to about 30 percent of the nation’s ground water used for irrigation.

Additionally, the aquifer provides drinking water to 82 percent of the people who live within the aquifer boundaries.

“The intense use of ground water has caused major declines in groundwater levels in parts of the High Plains over the past half century. Rates of withdrawal rose rapidly from the 1940s to the late 1970s but have declined or held steady in many areas since that time,” said Dr. Robert Hirsch, USGS associate director for water.

The report “Water in Storage and Approaches to Groundwater Management, High Plains Aquifer, 2000,” USGS Circular 1243, also includes a state-by-state summary of approaches to groundwater management in the eight states overlying the aquifer. It can be obtained by contacting USGS Information Services at 1-888-ASK-USGS.
Provided by theEnvironmental News Service.