Black Hawk Lake is the southern-most glacially formed lake in Iowa’s Sac County. This 922-acre body of water is a popular recreation area, attracting boaters, anglers and waterfowlers from across the state.
Despite its popularity, the lake has always suffered from degraded water quality. Over the years, the Iowa Department of Natural Resources has spent a considerable amount of time, effort and funding to improve water quality but with limited success. Non-native common carp are a major contributor to water quality issues and managing carp is key to maintaining better water quality in the lake long-term.
As part of the solution, Ducks Unlimited in 2021 designed and constructed a new fish barrier to prevent carp from migrating between the main body of the lake and the large marsh known as Provost Bay or the Inlet Bay.
This 160-acre marsh attracts significant numbers of waterfowl during migration and is popular with waterfowl hunters. Carp had damaged this important habitat by uprooting aquatic vegetation and competing with ducks for food. The new fish barrier will prevent carp from entering the marsh to spawn, thus decreasing the population, reducing turbidity and increasing the amount of food for waterfowl.
The new fish barrier design also included a pump system that will allow DNR managers to occasionally manipulate water levels and promote healthy wetland vegetation.
This $900,000 project was made possible by contributions from Ducks Unlimited, Iowa DNR Lake Restoration Program, the North American Wetlands Conservation Act, the City of Lake View and the Black Hawk Lake Protective Association.