High phosphorus levels and algal overgrowth are causing serious water quality issues for Lake Mitchell in South Dakota. For the past several summers, the city of Mitchell has issued health warnings associated with the agal blooms and advised people to stay out of the water and not allow pets to swim in the lake. The city decided to make big changes to improve water quality in the lake, and Ducks Unlimited is partnering with them to help.
Lake Mitchell is a man-made reservoir built in 1928 to provide drinking water and recreation opportunities. The lake's water quality gradually declined, due to sedimentation and excess nutrient runoff from agriculture fields throughout the Firesteel Creek watershed. While no longer a source of drinking water for the community, Lake Mitchell provides outdoor recreation and benefits the local economy.
"We can improve water quality in the watershed by restoring wetlands and creating buffers that shield surface waters from the runoff from croplands and livestock operations," said Bruce Toay, DU manager of conservation programs in South Dakota.
The city received a North American Wetlands Conservation Act
(NAWCA) grant to enhance water quality throughout the Firesteel Creek watershed, using natural features like wetlands and grasslands. Conservation easements will help agriculture operations in the watershed protect habitat and restore marginal cropland to wetlands and grasslands. These restorations will filter excess nitrogen and phosphorus from runoff water and prevent sediment from ending up in Lake Mitchell. Conservation easements provide a financial incentive for the landowner, protect wildlife habitat and contribute to water quality.
The city hired DU's engineering staff to survey and design a low-rise dam and settling ponds upstream of Lake Mitchell. These ponds will act as wetlands, capturing sediment and filtering pollutants to improve the quality of the water entering the lake.
This is the first NAWCA grant awarded to Mitchell for this multi-partner effort. The comprehensive plan will improve water quality of Lake Mitchell and conserve wetlands in the Prairie Pothole Region of South Dakota.