Posted on Dec 08, 2021
On December 8, Dr. Ryan Bailey of CSU’s Department of Civil and Environmental Engineering gave us a sobering but hopeful presentation on the history, current state, and future possibilities for the Ogallala aquifer, a fresh-water containing sand formation that underlies parts of eight Western states, including eastern Colorado.  This formation is one of the chief sources of irrigation water for the growth of corn, soy, cotton, wheat, sorghum, and cattle in those seven states.  It is responsible for some 30% of the total crop and animal production in the U.S., it provides some 30% of the irrigation water used in the U.S., and it generates some $35 billion in agricultural products annually.  The important starting data point is that the aquifer underlies a large area with average rainfall of 12 to 33 inches per year, less than is needed for most of the current agricultural production of the area.
Dr. Bailey started by introducing us to the structure of the Ogallala aquifer and the mechanics of extraction of water from that aquifer.  The aquifer sits on an impermeable bedrock so that no water that is in the formation can filter down into deeper formations.  The lower part of the aquifer has all of its pore spaces filled or saturated with water; the top of the saturated part is the “water table”, which may be some 100 to 200 feet below ground level.  Above the water table, the pores are filled mostly with air.  In order to extract water, a well is drilled to below the water table and lined with a screen to keep the sand of the formation from entering the well.  Then water is pumped to the surface.  The rate of withdrawal is highly variable both geographically and with time, depending on rainfall variability and the number of wells in place.  There is always some recharge from rain or other surficial water sources, but over most of the area recharge is less than withdrawal, so the ground water supply is decreasing.  This imbalance is most pronounced in the south (Texas, New Mexico, Oklahoma) whereas in much of Nebraska, the amount of water has remained more or less stable. 
The nature and scale of the problem are illustrated by “animated” maps showing the rapid increase in the number of center-pivot wells emplaced (beginning with their first introduction around 1970), the rapid rate of groundwater usage ramping up in the late 1960s and only slowly tapering off starting in the late 1980s, and the gradual and then more rapid reduction in saturated thickness of the reservoir starting shortly after World War II. 
One of the organizations working to counteract this depletion of the aquifer is the Ogallala Water Coordinated Agricultural Project (OWCAP), a grouping of some ten State and National organizations (including CSU) including some 70 individuals of various academic and technical backgrounds conducting integrated research on the problem and funded from 2016 through 2021 by the USDA-NIFA.  One of their main approaches has been to survey growers about their attitudes with respect to groundwater conservation.  Most respondents (86%) said that saving groundwater would decrease their production with about 2/3 saying that they don’t want to change their irrigation practices.  On the other hand, 2/3 or more generally agreed that groundwater should be conserved today in order to preserve future opportunities. 
From a practical, hands-on point of view, the organization has been pushing technological approaches to optimizing irrigation-water application, has developed and implemented an education program on crop/irrigation management (from which the trained farmers can go back to their communities and pass on those learnings), and have been modeling the impact of various groundwater strategies over the coming decades. The modeling seems to show that with the best strategies the rate of groundwater depletion and associated crop-production decrease can only be significantly reduced but not eliminated.  However, they are working with local groundwater management districts to implement and test solutions.