Saturated thickness and water in storage in the High Plains aquifer, 2009, and water-level changes and changes in water in storage in the High Plains aquifer, 1980 to 1995, 1995 to 2000, 2000 to 2005, and 2005 to 2009

The High Plains aquifer underlies about 112 million acres (about 175,000 square miles) in parts of eight States—Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. Water levels declined in parts of the High Plains aquifer soon after the onset of substantial irrigation with groundwater (about 1950). This report presents the volume of saturated aquifer material and drainable water in storage in the High Plains aquifer in 2009; water-level changes in the High Plains aquifer from 1980 to 1995, 1995 to 2000, 2000 to 2005, and 2005 to 2009; and changes in the volume of drainable water in storage in the aquifer from 1980 to 1995, 1995 to 2000, 2000 to 2005, and 2005 to 2009. The volume data were calculated from raster files with a cell size of about 0.6 acres. The volume of water in storage in the High Plains aquifer in 2009 is estimated at about 3.0 billion acre-feet. Area-weighted, average water-level changes for the aquifer were declines of 2.0 feet from 1980 to 1995, 1.3 feet from 1995 to 2000, 2.8 feet from 2000 to 2005, and 1.0 foot from 2005 to 2009. Estimated changes in water in storage were declines of 36.0 million acre-feet from 1980 to 1995, 23.5 million acre-feet from 1995 to 2000, 46.7 million acre-feet from 2000 to 2005, and 18.3 million acre-feet from 2005 to 2009.