Preserving Cedar Lake: A case study on successful source water protection in Winterset, Iowa

Winterset, Iowa, is well known for being the birthplace of American film icon John Wayne. The city is also well known for Cedar Lake, which has been a reliable source of drinking water for the city's residents. However, the lake has faced difficulties due to high watershed levels, silt intrusion, nutrient contamination and infrastructure needs. To tackle these challenges, the city launched a source water protection (SWP) program, which safeguards the water supply and now serves as a model for other communities facing similar water quality concerns.

Vision and Development
Winterset created a SWP program to address pressing issues affecting Cedar Lake. "Cedar Lake had struggled for years from watershed influences, including a high watershed-area-to-lake-size ratio, predominantly from farming systems, including livestock," said Tim Palmer, watershed manager for the Winterset Water Department. The large watershed area relative to the lake results in a consistently high lake surface area. However, this causes an influx of silt, nutrients and chemicals from the watershed into the lake. Silt intrusion had gradually reduced the lake's capacity, rendering it vulnerable to dry periods and necessitating increased supply management. Additionally, the rich farmland in the watershed, with tile drainage systems, raised concerns about elevated nitrate levels during specific periods. These issues prompted the installation of a reverse osmosis nitrate removal system.

Collaborative Goal Setting
Winterset's SWP plan entailed collaboration with diverse stakeholders and the formation of a source water protection team. This collaborative approach was instrumental in tackling water quality challenges. Palmer emphasizes that "Cedar Lake Watershed has long been a priority for the Madison County Soil and Water Conservation District," enabling a concerted effort to implement conservation practices that enhance water quality while preserving farmland productivity.

Agricultural Partnerships and Strategies
The program's success also hinged on partnerships with local agricultural stakeholders and organizations. These partnerships facilitated the adoption of best management practices (BMPs) and soil health practices, including the establishment of Conservation Reserve Enhancement Program (CREP) wetlands. "These wetlands efficiently capture and filter water from tile-drained land, removing substantial nutrients, primarily nitrates," said Palmer.

Action Plan and Implementation
The Winterset SWP program also involved a comprehensive action plan, which included components like grass waterways, intake terraces, biofilters, saturated buffers and small wetlands. These strategic components effectively control water flow and improve water quality before reaching Cedar Lake.

Community Engagement and Public Awareness
A small but passionate group of residents, producers and local leaders drives community engagement around the SWP plan, which is key to the program's success. "Keeping customers informed about water supply concerns and fostering partnerships with conservation districts and local leaders have been pivotal," said Palmer.

Adapting to Changing Land Use
As Winterset continues to grow, the SWP program remains adaptable, updating zoning ordinances to encompass runoff treatments and mitigate pollutants. Proactive measures are implemented to address potential risks to source water quality, ensuring a sustainable water supply for the expanding city. The water utility has historically helped landowners in the watershed offset a portion of the costs of implementing water quality measures to protect the investments in the lake and water supply infrastructure.

The source water protection program in Winterset teaches valuable lessons on innovative thinking, long-term planning, and coordinated efforts to manage watersheds for various goals. This approach is comprehensive, collaborative, and adaptable, making it a great example for other small systems facing similar challenges.