Water-Level Changes in the High Plains Aquifer, Predevelopment to 2007, 2005–06, and 2006–07

The High Plains aquifer underlies 111.6 million acres (174,000 square miles) in parts of eight States—Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. Water-level declines began in parts of the High Plains aquifer soon after the beginning of substantial irrigation with ground water in the aquifer area. This report presents water-level changes in the High Plains aquifer from the time before substantial ground-water irrigation development had occurred (about 1950 and termed “predevelopment” in this report) to 2007, from 2005–06, and from 2006–07. The report also presents the percentage change in saturated thickness of the aquifer, from predevelopment to 2007. Measured water-level changes from predevelopment to 2007 ranged from a rise of 84 feet in Nebraska to a decline of 234 feet in Texas. The area-weighted, average water-level changes in the aquifer were a decline of 14.0 feet from predevelopment to 2007, a decline of 0.4 foot during 2005–06, and a decline of 0.6 foot during 2006–07. Total water in storage in the aquifer in 2007 was about 2.9 billion acre-feet, which was a decline of about 270 million acre-feet since predevelopment