Total Maximum Daily Loads (TMDLs)

Total Maximum Daily Loads (TMDLs) are EPA approved amounts of pollutant loading that can occur and have a water body meet water quality standards. This page is collection of links and resources to better understand, and meet, TMDL requirements.

Confluence of the St. Croix and Mississippi rivers. Note the St. Croix River is not impaired for sediment, while the Mississippi River is impaired.

TMDL MS4 permit guidance

• Forms, guidance, and resources for completing the TMDL annual report form
• Link to many TMDL GIS shapefiles
• Summary of TMDL requirements in stormwater permits
• Guidance for meeting chloride TMDL MS4 permit requirements
• Guidance for meeting bacteria TMDL MS4 permit requirements
• Guidance for meeting dissolved oxygen or oxygen demand TMDL MS4 permit requirements
• Guidance for meeting temperature TMDL MS4 permit requirements
• Guidance for categorical TMDLs
• List of Approved TMDLs with MS4 WLAs
• Guidance for completing the MS4 Permit TMDL Application Form
• MS4 webinars and videos
• Baseline year
• Interpreting wasteload allocations based on flow/load duration curves
• Information about the 2019 Legislation and affected MS4s

TMDL toolkit for MS4 permit compliance

Access a quick guide for using models to meet MS4 TMDL requirements

• Overview of models used to meet MS4 TMDL permit requirements
• P8
  • Recommendations and guidance for utilizing P8 to meet TMDL permit requirements
  • Case study for using P8 to meet TMDL permit requirements
  • U of MN P8 training on the use of the P8 software. P8 is a free software package for modeling stormwater pollutant management in urban watersheds. This training will be offered online through zoom in the afternoons of March 2 and March 3, with a short session on February 23 to confirm software installation and access. For more information on this training, go to this link.
• WINSLAMM
  • Recommendations and guidance for utilizing WINSLAMM to meet TMDL permit requirements
  • Case study for using WINSLAMM to meet TMDL permit requirements
• MIDS (Minimal Impact Design Standards calculator)
  • Recommendations and guidance for utilizing the MIDS calculator to meet TMDL permit requirements
  • MIDS calculator
  • Case study for using the MIDS calculator to meet TMDL permit requirements
• MPCA Simple Estimator
  • Recommendations and guidance for utilizing the MPCA Simple Estimator to meet TMDL permit requirements
  • Guidance and examples for using the MPCA Estimator
  • Case study for using the MPCA Simple Estimator to meet TMDL permit requirements
  • MPCA review of submittals using the MPCA Simple Estimator
  • Default TSS and TP loads for different land use scenarios using the MPCA Simple Estimator
• Monitoring
  • Recommendations and guidance for utilizing monitoring to meet TMDL permit requirements
  • Recommendations and guidance for utilizing lake monitoring to meet TMDL permit requirements
  • Recommendations and guidance for utilizing stream monitoring to meet TMDL permit requirements
  • Recommendations and guidance for utilizing major stormwater outfall monitoring to meet TMDL permit requirements
  • Recommendations and guidance for utilizing stormwater best management practice monitoring to meet TMDL permit requirements
• Quick guides for using models to meet MS4 TMDL permit requirements
• Case studies for monitoring to meet TMDL permit requirements

TMDL guidance and general information

• Overview of TMDLs
• Technical guidance used by MPCA to develop guidelines for setting TMDL WLAs for regulated stormwater
• Guidance on what discharges should be included in the TMDL wasteload allocation for MS4 stormwater
• Construction activity by county
• Training modules
  • Overview of Stormwater Effects on Water Quality - File:Wq-strm7-81.pdf
  • Construction, Industrial & Municipal Stormwater Permits & SWPPPs - File:Wq-strm7-82.pdf
  • The TMDL Process as it Relates to Stormwater - File:Wq-strm7-83a.pdf
  • TMDL Stormwater Language - File:Wq-strm7-84a.pdf
  • Setting Wasteload Allocations in a TMDL - File:Wq-strm7-84b.pdf
  • Meeting Requirements of a TMDL - File:Wq-strm7-85a.pdf

Information received from MS4 permittees

• Summary of data received from permittees on MS4 TMDL permit reporting forms

Links and other resources

• Visit the MPCA TMDL Project page for information on specific projects across the state
• Total Suspended Solids (TSS)
• Phosphorus
• Bacteria in stormwater
• Protection and restoration of receiving waters