GLSD Compliance with TMDL Requirements

As we focus heavily on the health of Green Lake, it is important to note that we are part of a greater watershed – the Upper Fox/Wolf Basins. As an impaired waterbody, the health of Green Lake is a concern to the DNR and the federal government as well. Water from Green Lake makes its way into Lake Winnebago and ultimately into the Lower Fox River Basin where it outlets into Green Bay. The waters located within the Upper Fox/ Wolf Basins are designated as impaired due to excess phosphorus and total suspended solids (TSS).

The Federal Clean Water Act requires states to identify and restore impaired waterbodies. To restore waters within the Fox/Wolf Basins, the DNR developed a Total Maximum Daily Load (TMDL) for phosphorus and total suspended solids being discharged into the Fox/Wolf Rivers. The TMDL identifies the sources of the pollutants and the reductions necessary to address water quality impairments. To restore water quality in the Winnebago Lakes as well as the Lower Fox basin, restrictions on phosphorus and TSS discharge have been placed on wastewater treatment facilities. Additionally, the DNR is working with various watersheds throughout the Fox/Wolf basins to limit non-point source phosphorus loading (generally from streambank erosion and urban and agricultural runoff). These non-point source reductions benefit our local waterbodies but ultimately reduce loading downstream into the Lower Fox River and Green Bay.

How this impacts the Green Lake Sanitary District is twofold. In our efforts to fund best management practices (BMPs) in the watershed, the GLSD is further able to capitalize on the DNR’s non-point source reduction grants. This funding will continue the focus of the District and our partners on improving the quality of the water entering the lake. We are cautiously optimistic about our future watershed protection efforts.

The second way the TMDL impacts the GLSD is specific to our role as a wastewater treatment facility. The DNR has dramatically decreased the amount of phosphorus we will be able to discharge to the Fox River beginning in 2026. Many people do not realize that the GLSD does not discharge into Green Lake or any of our tributaries. Our treated effluent is discharged through an 8” force main pipe that extends around 5.5 miles to the Fox River south of the City of Princeton. Like most other wastewater municipalities in WI, the GLSD is in the process of researching our best options to meet the TMDL requirements. This research has the District working closely with the DNR as well as our wastewater consultants at Cedar Corporation. Several compliance options have been identified as suitable for us as a two-cell aerated lagoon treatment facility. We are currently weighing environmental impacts, long-term feasibility, costs, and staffing needs for the various options. We hope to have additional information for our customers as we move through the compliance process.