Wisconsin Stormwater Management (2026)

Key Facts

Code: NR 151 / Wis. Stat. 281.33
Permit threshold: 1+ acre disturbed
TSS reduction: 80 percent new sites
Max forfeiture: $10,000 per day

Full Breakdown

Wis. Stat. section 281.33 and Wis. Admin. Code NR 151 establish runoff management standards applicable to construction sites disturbing one acre or more, municipal separate storm sewer systems (MS4s), and certain land uses. Post-construction sites must reduce total suspended solids by 80 percent for new development. Construction operators must obtain a WPDES general permit, install erosion controls, and submit stormwater management plans. Municipalities designated as MS4s must implement six minimum control measures, including public education, illicit discharge detection, and post-construction controls. Local rules may be stricter but must satisfy NR 151 baselines.

Violations & Penalties

DNR may issue notices of violation, daily forfeitures up to $10,000 under Wis. Stat. 281.98, stop-work orders, and require remediation of unauthorized discharges.

Frequently Asked Questions

When is a stormwater permit required in Wisconsin?

Construction projects disturbing one or more acres of land must obtain a WPDES construction site general permit from the DNR before earth-disturbing work begins.

Do these rules apply on private property?

Yes. NR 151 standards apply to construction and post-construction sites regardless of ownership when acreage thresholds are met or local MS4 ordinances apply.

Can my city require stricter stormwater controls?

Yes. Local governments may adopt stricter standards, but they cannot fall below the NR 151 minimum performance standards established by the DNR.

Wisconsin Stormwater Discharge and NR 151 Standards