On behalf of Green Lake Association (GLA) in central Wisconsin, USA, The Water Council is managing a Request for Information (RFI) seeking effective and proven technologies, materials, nature-based systems, or engineered solutions for addressing excessive phosphorus and duckweed loading in ambient waters.
Green Lake is Wisconsin’s deepest two-story glacial lake covering an area of 7,660 acres and is listed as an impaired water body for low dissolved oxygen (DO) caused by phosphorus loading (formerly an oligotrophic lake and now listed as an impaired metalimnetic oxygen minima caused by phosphorus). Multiple studies have been performed and it is estimated that Green Lake will need a 50-70% reduction in controllable phosphorus loading (16,625 pounds per year) to meet its water quality goals.
Hundreds of best management practices (BMPs) are already being executed and, in 2023 alone, lake management partners expect over $1.1M USD in grant funding for watershed BMPs. It is known that nearly 80% of annual phosphorus loading flows through two shallow estuaries, on the west and east ends of the lake, entering the main waterbody under two bridges. The eastern estuary is also the primary location of duckweed production on Green Lake.
The GLA is interested in exploring solutions and technologies to complement their BMPs and intercept the phosphorus inflow from these two primary loading sources (pinch points). Some conceptual ideas include but are not limited to: 1) sediment inactivation (internal loading capping), 2) phosphorus interception (in-stream treatment), 3) nutrient reduction facilities (off-line treatment solutions), 4) wetland restoration, and/or 5) duckweed harvesting.
Additional information and background can be viewed below.
Innovative, commercially ready and deployable solutions, technologies or engineered solutions are sought for this RFI including proven solutions which:
Disclaimer: This is a request for information (RFI) ONLY to learn about solutions to mitigate phosphorus as described above. There is NO funding, prize, pilot, or outcome other than collecting applications for review and evaluation. The GLA will review all submissions and determine which solutions may be considered for follow-up meetings or exchange of additional information.
Approach 1: Internal Loading Treatment / Sediment Inactivation
Approach 2: In-Stream Treatment / Phosphorus Mitigation
Approach 3: Off-line Treatment / Nutrient Reduction Facilities
Approach 4: Wetland Restoration
Approach 5: Duckweed Harvesting