Guidance for meeting temperature TMDL MS4 permit requirements
This page will be developed in August/September, 2019
Contents
DRAFT Temperature TMDL WLA Guidance (MS4 General Permit Section 22)
Total Maximum Daily Loads (TMDLs)
Currently there are two approved total maximum daily load (TMDLs) for Brown’s Creek and Miller Creek that include MS4 (Municipal Separate Storm Sewer System) wasteload allocations (WLAs) for thermal loading. Brown’s Creek is impaired for aquatic life due to a lack of cold water fish assemblage. Miller Creek is impaired for aquatic life due to a lack of cold water fish assemblage and elevated water temperature.
Requirement (Permit Section 22.7)
If the permittee has an applicable WLA for temperature that includes a reduction greater than zero percent, the permittee must maintain a written plan that identifies specific activities the permittee will implement to reduce thermal loading during the permit term (Table 1). The written plan may include, but is not limited to: a. implementation of infiltration BMPs such as bioinfiltration practices; b. disconnection and/or reduction of impervious surfaces; c. retrofitting existing structural stormwater BMPs; and d. improvement of riparian vegetation.
MS4s with applicable temperature WLAs
Link to this table
| TMDL Project | MS4 with a WLA for temperature |
|---|---|
| Browns Creek TMDL | Stillwater City |
| Miller Creek TMDL | Duluth City |
| Hermantown City | |
| Rice Lake City | |
| MnDOT Outstate | |
| St. Louis County | |
| University of Minnesota-Duluth | |
| Lake Superior College |
Information on potential BMPs/activities that may be included in the written plan to reduce heat to Brown’s Creek and Miller Creek are available in the following:
Brown’s Creek TMDL
- Brown’s Creek Impaired Biota TMDL
- Brown’s Creek TMDL Implementation Plan
- Brown’s Creek Watershed District 2017-2026 Watershed Management Plan