Ground water withdrawals for crop irrigation have increased to more than 16 million acre-feet per year in the High Plains Aquifer, according to a recent U.S. Geological Survey (USGS) study.

The USGS study shows that recharge, or the amount of water entering the aquifer, is less than the amount of ground water being withdrawn, causing groun dwater losses in this already diminished natural resource. Crop irrigation is the largest use of ground water in the aquifer, and, for the past 60 years, has caused severe water-level declines of up to 100 feet in some areas. The new USGS findings address concerns about the long-term sustainability of the aquifer.

"The High Plains Aquifer is NATURE'S nearly perfect water storage system: self-recharging, safe from natural disasters, readily accessed over a broad area, and with copious capacity," says USGS Director Marcia McNutt. "And yet in less than 100 years, we are seriously depleting what took Nature more than 10,000 years to fill."

The High Plains aquifer underlies about 175,000 square miles in parts of eight states – Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas and Wyoming – and is a major source of ground water irrigation in the region. The High Plains region supplies approximately one-fourth of the nation’s agricultural production.

"Because ground water losses are greater than recharge, water levels in many parts of the aquifer are currently declining," says Jennifer Stanton, USGS scientist and an author of the report. "Such information can inform ground water management decisions made by state and local agencies."

The new USGS study also compares previously published data with new methods for estimating recharge and ground water withdrawals, and provides an assessment of the strengths and weaknesses of those methods. 

This USGS report is part of a larger study to evaluate ground water availability of the High Plains Aquifer. The study is being conducted through the USGS Groundwater Resources Program (http://water.usgs.gov/ogw/gwrp/) to assist state and local ground water management agencies and to assess the status of ground water resources from a national perspective.

Clickhereto access the full report.