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DRAFT Temperature TMDL WLA Guidance (MS4 General Permit Section XX)

Total Maximum Daily Loads (TMDLs)

Currently there are two approved TMDLs for Brown’s Creek and Miller Creek that include MS4 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 21.10)

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 dissolved oxygen/oxygen demand WLAs
Link to this table

TMDL Project MS4 with a WLA for oxygen demand
Hardwood Creek Impaired Biota and Dissolved Oxygen TMDL Anoka County
Hugo City
Lino Lakes City
MNDOT Metro District
Rice Creek Watershed District
Washington County
Trott Brook (Rum River Watershed TMDL) Elk River City
Nowthen City
Ramsey City
Saint Francis City
Sherburne County
Buffalo Creek (South Fork Crow River Watershed TMDL) Glencoe City