Dodge City's water reuse project
The beef cattle industry is very important to the state of Kansas as a whole18 and to Dodge City, located in south-western Kansas, in particular. Confined feed yards near Dodge City fatten cattle for slaughtering, rendering, packing and shipping, both for domestic and international purposes. The city relies on groundwater for its municipal water supply, which covers household, commercial and industrial (beef plant) uses. Faced with the cost of constructing an expensive wastewater treatment plant in the 1980s, Dodge City opted instead to pipe its municipal wastewater 17 km south of the city to large ponds, where the wastewater undergoes aerobic and anaerobic treatment. A farming operation then applies this wastewater for irrigating maize, milo and lucerne, thus saving the farmers the cost of buying nitrogen and other plant nutrients.
Before this water reuse project was constructed, the participating farmers had drawn freshwater from the aquifer for irrigation purposes. The city constructed the wastewater ponds near the farmers' wells and irrigated fields. The 1987 agreement between the farmers and the city provided that in exchange for the use of wastewater for a 40-year term, the farmers would lease their groundwater rights to the city, except for small amounts of water needed to dilute the treated wastewater. The city, however, did not use the groundwater under its lease from 1987 to 2004.
Recent growth in population and industry has caused the city to increase the wastewater treatment capacity at the ponds and commence use of the groundwater rights under lease for municipal purposes. For this expansion, the project participants face several legal and scientific issues and challenges to insure continued success. The change in groundwater rights is one such problem. Permission is required from the DWR to change the type of use (irrigation to municipal), place of use (farms to city) and points of diversion (old irrigation wells to new municipal wells) (Kansas Statutes Annotated, 2005, §82a-708b). A water quality challenge is to avoid applying low-quality water that would harm the plants and pollute the groundwater. Optimizing the quality and quantity of the irrigation water insures high crop yields and high-quality groundwater over time. Measures are used prior to pond treatment to remove some pollutants. Cropping choices and wastewater application schedules by the farmers are important. They must observe a fine balance: on the one hand they must maintain profitability in their farm operations, but on the other hand they must minimize pollutant migration to the groundwater by optimizing nutrient uptake and usage by the plants. As the city and its industries grow, so does the contractual obligation of the farmers to accommodate more wastewater for irrigation, requiring the farmers to acquire additional crop land.
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