CORVALLIS, Ore., Nov. 18 (UPI) -- Great Plains river basins are threatened by pumping of groundwater from aquifers, risking a bleak future for native fish in many streams, U.S. researchers say.
Unlike alluvial aquifers, which can be replenished with rain and snow, these regional aquifers were created by melting glaciers during the last Ice Age, the researchers say, and when that water is gone, it's gone for good.
"It is a finite resource that is not being recharged," Jeffrey Falke, a researcher at Oregon State University and lead author on the study, said.
"That water has been there for thousands of years, and it is rapidly being depleted. Already, streams that used to run year-round are becoming seasonal, and refuge habitats for native fishes are drying up and becoming increasingly fragmented."
In a three-year study of the Arikaree River in eastern Colorado, researchers concluded that during the next 35 years only slightly more than half of the current fish refuge pools would remain.
Falke and his colleagues say it would require a 75 percent reduction in the rate of groundwater pumping to maintain current water table levels and refuge pools, which is "not economically or politically feasible," the study said.
Pumping of regional aquifers is done almost entirely for agriculture, Falke said, with about 90 percent of the irrigation aimed at corn production, along with some alfalfa and wheat.