11 Hydrogeologic Problems in the Midwestern U.S

Monday, 24 March 2003
1:00 PM - 5:00 PM

IF YOU LOOK FOR IT YOU WILL FIND IT – WATER QUALITY PROBLEMS IN KANSAS

Paper number: 11-2
Program: THEME SESSIONS
Time: 1:15 PM – 1:30 PM

Authors

Abstract

Ground water is a major source of water for the western two-thirds of Kansas. Approximately 4% of the ground water is used by municipalities and 89% is used for irrigated agriculture. Potential sources of nitrate include fertilizer and animal waste both from feedlots and septic systems. Evaluation of nitrate sources in different ground water systems shows that in alluvial systems 40% of the samples indicated animal waste sources and 33% indicated fertilizer. In the High Plains aquifer in south-central Kansas 50% of the samples indicated a fertilizer source and 22% indicated animal waste. In the deeper Ogallala aquifer, 9% showed animal waste sources, 26% showed fertilizer, and 39% showed the effects of denitrification enrichment. Approximately 20 to 25% of all of the samples showed mixed sources that could not be identified.

Areas with permeable unsaturated zones and shallow water tables are the most impacted by nitrate contamination. However, recent work by the USGS NAWQA program showed that in deep aquifer systems, such as portions of the Ogallala aquifer in western Kansas, both the vadose zone and the water table have measurable agchemicals, nitrate, and tritium suggesting a faster recharge to the deep ground water than previously expected. Comparisons of water chemistry sampled from the same wells in the 1970’s and the 1990’s show an increase in nitrate, chloride, and sulfate. All of these parameters impact the quality and usability of water by different users.

In the deep aquifer systems there is a substantial lag time between prior land use practices and the impact on current water quality. Under current land use practices it is anticipated that future water quality will continue to deteriorate. Unless management practices are changed in this region of the state, both the quality and quantity of water may leave future users high and dry.