Oshkosh staff weigh tougher stormwater code to meet TMDL targets; council seeks cost and development impact data

Oshkosh City staff and a Brown and Caldwell consultant reviewed proposed updates to the city’s stormwater code in a workshop focused on how the municipal separate storm sewer system (MS4) permit and the Upper Fox‑Wolf watershed total maximum daily load (TMDL) affect local requirements.

Consultant Chuck Boehm, Brown and Caldwell’s client services director for Wisconsin, told the workshop the state DNR expects municipalities covered by MS4 permits to “show continued progress” toward TMDL reductions but that the current MS4 language does not set a single near‑term compliance deadline. “We’re not going to be required to meet those numbers tomorrow or 5 years or 10 years or maybe even 50 years,” Boehm said, describing how DNR has approached stormwater compliance differently than point‑source permits.

Staff said the city is considering several ordinance scenarios that would change the pollutant‑reduction standards developers must meet during site plan review. Under current Chapter 14 language, Oshkosh requires reductions of about 40% total suspended solids (TSS) for redevelopment and 80% for new development; the proposed scenarios add numeric phosphorus (total phosphorus, TP) targets and, in some cases, raise TSS targets in certain drainage basins. Two options the team said it favors are a basin‑specific…