Facing new phosphorus limits for its wastewater treatment facility (WWTF) as mandated by the Upper Fox-Wolf Total Maximum Daily Load rule, the Stephensville Sanitary District took proactive steps to meet these requirements sustainably. Working with Ruekert & Mielke, the District explored Water Quality Trading (WQT) to balance phosphorus levels while achieving cost savings and operational efficiency.

Currently, the District uses a chemical coagulant to manage phosphorus levels. However, the narrow treatment range meant that even minor fluctuations could risk exceeding the effluent limit. To address this, the District sought WQT credits to secure a more robust compliance buffer. This approach not only enhanced phosphorus control but also allowed for reduced chemical use, cutting costs and producing less sludge.

Farmland along Bear Creek

Initially, the District contacted local landowners along Bear Creek, the WWTF’s discharge tributary, to propose runoff reduction practices. Supported by the Outagamie County Land and Water Conservation Department, the District engaged farmers by covering upfront costs for runoff reduction practices and any land removed from production. Despite informational meetings and site visits, the response from landowners was limited.

Shifting gears, the District partnered with the Wisconsin Water Quality Clearinghouse, a state-supported program connecting phosphorus credit buyers (like municipalities) with credit generators (typically farmers). The Clearinghouse streamlined the WQT process, leveraging its network and online portal to connect the District with a farmer willing to implement a runoff-reduction project that could yield the necessary 25 pounds per year of phosphorus reduction.

In early 2024, the District and the Clearinghouse established a 10-year credit agreement for a wetland restoration project. This project involves re-routing waste and runoff, and reestablishing marsh areas and dikes to naturally manage runoff and improve water quality. Notably, the Clearinghouse model transfers WQT responsibilities—such as preparing trading plans, modeling credit impacts, and performing inspections—from the District to the credit generator, easing municipal management of WQT.

With a planned completion in summer 2025, the final project will include a deed-linked three-party agreement between the farmer, the District, and the Clearinghouse. This innovative collaboration promises a sustainable solution for phosphorus control, allowing the District to meet regulatory standards with reduced chemical use, lower costs, and enhanced environmental impact.

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About the Author

David Arnott, P.E.
Team Leader/Senior Project Manager

Dave has extensive experience in the planning, design and construction project management of wastewater treatment facility renovation and upgrade projects. Areas of expertise include treatment processes, hydraulics, mechanical equipment, and wastewater disinfection. He also has experience in sanitary and water pumping station design and sanitary sewer wet weather facilities.