Agricultural Water Conservation in the High Plains Aquifer and Arikaree River Basin

Abstract

Yuma County is the top crop producing County in Colorado that is dependent on groundwater supplies from the High Plains aquifer for irrigation. The Arikaree River, a tributary of the Republican River in eastern Colorado, is supplied with water from the High Plains aquifer. The Arikaree River alluvium is also a habitat for many terrestrial invertebrates and the threatened Hybognathus hankinsoni (Brassy Minnow). The constant demand on the High Plains aquifer has created declining water levels at the linear rate of 0.183 m/year with the deepest pool in the Arikaree River drying up in 8 to 12 years. In addition to the demands for habitats, the surrounding irrigated agricultural lands require water for crop production. These challenges are currently confronting farmers in eastern Colorado and this research presents possible alternatives to meet these demands. This research presents a combination water balance model, water conservation model, and water conservation survey results from farmers in eastern Colorado to identify alternatives to extend the life of the Arikaree River. The first alternative was to examine the reduction in irrigation water from removing the 18 allu- vial irrigation wells that could extend the Arikaree River pools from drying up for 30 years. The other scenario found that water conservation practices with participation of 43%, 57%, and 62% of farmers would extend the drying time to 20, 30, and 40 years, respectively. The final alternative studied was the required participation in conservation practices to stop the decline of the High Plains Aquifer. The analysis found that 77% participation of farmers in all conservation alternatives or reducing pumping by 62.9% would be necessary to stabilize the High Plains Aquifer.