From The Pueblo Chieftain (Chris Woodka):
Wells are depleting the High Plains Aquifer at an alarming rate, according to a study released last week by the U.S. Geological Survey.
“The measurements made from 2011 to 2013 represent a large decline,” said Virginia McGuire, USGS scientist and lead author of the study. “This amount of aquifer depletion over a two-year period is substantial and likely related to groundwater pumping.”
The aquifer, also known as the Ogallala Aquifer underlies 175,000 square miles in Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas and Wyoming.
Wells began tapping the aquifer heavily in the 1930s and 1940s, and the acreage irrigated expanded to 15.5 million acres in 2005 from 2.1 million acres in 1949.
The total water stored in the aquifer in 2011 was estimated at 2.92 billion acre-feet (951.5 trillion gallons). Pumping in two years depleted that by 36 million acre-feet (11.7 trillion gallons), causing an average drop in the aquifer of 2.1 feet. The overall rate of decline in the entire aquifer since pre-development is 267 million acre-feet, or 8 percent, resulting in a drop of 15,4 feet through 2013.
The change has been most significant in Texas, where levels dropped 44 feet in some places in the 2011-13 study period and 256 feet since pumping began. In some places, the well levels rose. With the highest rise since predevelopment recorded in Nebraska at 85 feet. Over time, Texas well levels have declined by 41 percent, and Kansas wells by 25 percent. Colorado dropped 14.3 percent over that same period, with more severe declines in the northern part of the state.
For the 2011-13 period, 7,460 wells were studied, 411 of those in Colorado. For the pre-development study, 3,349 wells were included, with 325 in Colorado.
“This multi-state, groundwater-level monitoring activity tracks water-level changes in all eight states through time and has provided data critical to evaluating different options for groundwater management,” said McGuire. “This level of coordinated groundwater-level monitoring is unique among major, multi-state regional aquifers in the country.”
Here’s the release from the United States Geological Survey (Virginia L. McGuire):
The High Plains aquifer underlies 111.8 million acres (about 175,000 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 groundwater in the aquifer area (about 1950). This report presents water-level changes in the High Plains aquifer from predevelopment (generally before 1950) to 2013 and from 2011 to 2013. The report also presents change in water in storage in the High Plains aquifer from predevelopment to 2013 and from 2011 to 2013.
The methods to calculate area-weighted, average water-level changes; change in water in storage; and total water in storage for this report used geospatial data layers organized as rasters with a cell size of 500 meters by 500 meters, which is an area of about 62 acres. These methods were used to provide a raster dataset of water-level changes for other uses.
Water-level changes from predevelopment to 2013, by well, ranged from a rise of 85 feet to a decline of 256 feet. Water-level changes from 2011 to 2013, by well, ranged from a rise of 19 feet to a decline of 44 feet. The area-weighted, average water-level changes in the aquifer were an overall decline of 15.4 feet from predevelopment to 2013, and a decline of 2.1 feet from 2011 to 2013. Total water in storage in the aquifer in 2013 was about 2.92 billion acre-feet, which was a decline of about 266.7 million acre-feet since predevelopment and a decline of 36.0 million acre-feet from 2011 to 2013.
Click here to read the report.
More coverage of the 2012 drought and its affect on the Ogallala Aquifer from Stephanie Paige Ogburn writing for KUNC. Here’s an excerpt:
In Northeastern Colorado, farmers growing food like corn and potatoes depend for water on a giant, underground reservoir. Called the Ogallala, or High Plains aquifer, this water source spreads across eight high plains states like a giant, underground lake.
In times of drought, farmers who use the aquifer for water take more of it. A report from the U.S. Geological Survey, published December 16, shows the 2012 drought significantly diminished the Ogallala’s water.
“The bottom line was, there was with the drought, increased pumping and you have decline of the water levels,” said Virginia McGuire, the U.S. Geological Survey scientist who authored the report.
Over the last six decades, Colorado has exceeded the aquifer’s resupply by 18.8 million acre-feet of water. An acre-foot is the amount of water needed to cover an acre of land one foot deep.
Between 2011 and 2013, the state used up 3 million acre-feet more than was recharged. Across most of the aquifer, other areas also used a whole lot of water during that period. Kansas and Texas, both hard hit by drought, caused the largest declines in Ogallala water levels.
McGuire, who has been tracking the aquifer’s water level for years, said she knew the drought would make an impact. She was a little surprised at how significant an effect it was, though.
“The story is drought was widespread and there were declines in most of the aquifer for the 2011 to 2013 time frame.”
More Ogallala Aquifer coverage here.