Oshkosh Plan Commission recommends citywide stormwater standard (scenario 5, amended) to meet DNR water-quality goals

The Plan Commission on June 3 recommended that staff pursue a citywide post-construction stormwater ordinance update consistent with Scenario 5 and approved an amendment to raise the redevelopment total phosphorus (TP) target to 34.5 percent. The motion carried as amended by roll call vote 8-0.

Consultant Chuck Beam of Brown and Caldwell presented the study and analysis. He said the project focuses on stormwater water-quality standards (total suspended solids, TSS, and total phosphorus, TP) under the Wisconsin Department of Natural Resources (DNR) Total Maximum Daily Load (TMDL) framework for the Fox-Wolf basins, and that the city received a DNR grant to support the work. Beam explained the city’s current ordinance measures TSS reductions and that the TMDL study adds phosphorus targets. He noted the city meets many TSS targets in several watersheds but remains deficient in Sawyer Creek, where the DNR recommends a higher TSS reduction (about 58.4%).

Beam reviewed multiple scenarios combining different TSS and TP reduction targets for new development and redevelopment. Scenario 5 proposed a citywide approach using a TSS target (80% for new development and 58.4% for redevelopment equivalent) and corresponding TP targets; commissioners discussed whether to apply higher Sawyer Creek-specific numbers only inside that watershed (Scenario 3) or citywide (Scenario 5). Beam and city staff explained that higher numerical targets increase the likelihood developers will request relief under the ordinance’s "maximum extent practicable" (MEP) provision and that some technologies—particularly wet ponds and infiltration—are more effective for both TSS and TP removal than others.

Commissioners debated economic and practical trade-offs. Some members, including Commissioner Margaret Propp and Vice Chair Keefer, expressed caution about setting targets that would make routine projects infeasible; others, including Commissioner Kathy Davie (who referenced the Sustainability Board’s prior recommendation), urged stronger environmental action. A public commenter, Steve Atkins, a contractor considering moving to Oshkosh, cautioned that very high targets could prevent projects from being proposed and recommended focusing on enforcement of existing stormwater measures.

After discussion, Commissioner Perry moved to recommend Scenario 5. A friendly amendment to raise the redevelopment TP target from 30% to 34.5% was proposed and accepted; commissioners debated the amendment’s trade-offs and then approved the amended motion by roll call (8-0). Staff said the next step is to draft ordinance language for Common Council consideration and to take advisory-board input into account. Beam noted the city’s municipal stormwater permit is due for update and that adding a TP requirement is a minimum necessary step to align with DNR expectations.

Key numbers discussed: Scenario 5 TSS targets (new development 80%, redevelopment 58.4%); amendment sets redevelopment TP target to 34.5%. DNR TMDL targets for portions of the city included TP reduction targets up to ~85% in some reaches; Sawyer Creek TSS target cited as 58.4% and TP targets significantly higher in DNR analysis.