The Environmental Protection Agency (EPA) requires Washington State Department of Ecology (Ecology) to develop a TMDL for each water body segment that does not meet state water quality standards for a specific pollutant. A TMDL:
- Identifies pollution problems in a watershed.
- Specifies how much pollution needs to be reduced or eliminated.
- Provides targets and strategies to achieve clean water.
TMDLs in WSDOT's NPDES Municipal Stormwater Permit
The NPDES Municipal Stormwater Permit requires WSDOT to comply with requirements in applicable TMDLs approved by the EPA. Ecology, WSDOT’s Municipal Stormwater Permit administrator, adds new applicable TMDLs to WSDOT’s permit at least every 18 months. In March 2012, Ecology modified WSDOT’s permit and added 15 new TMDLs. The permit now includes 26 TMDLs statewide (pdf 671 kb).
The requirements we need to comply with differ in each TMDL.
- 8 TMDLs require us to comply with permit obligations that address the TMDL pollutant.
- 9 TMDLs require us to implement actions above and beyond our normal permit obligations, as defined in Appendix 3 of the permit.
- 9 TMDLs require us to apply our programmatic approach to address fecal coliform.
Appendix 3 (pdf 327 kb) of the permit lists WSDOT’s required action items and includes a flow chart of our fecal coliform programmatic approach.
Fecal Coliform Programmatic Approach
WSDOT’s programmatic approach (pdf 205 kb) to address fecal coliform streamlines the development of TMDL implementation plans and ensures WSDOT is required to perform applicable and appropriate action items. The actions WSDOT performs within TMDL boundaries as part of our fecal coliform programmatic approach include:
- Inventory of highway discharge locations.
- Illicit discharge detection and elimination (IDDE).
- Basic source identification for fecal coliform.
- Identification of maintenance issues.
For each of the TMDLs that require us to apply our fecal coliform programmatic approach, we create a Summary of Inventory Findings Report. We have completed these reports for:
Issaquah Creek Basin TMDL
Little Bear Creek TMDL
Swamp Creek Basin TMDL
Stillaguamish River TMDL
WSDOT also includes a TMDL implementation summary report as part of our Annual Stormwater Report (pdf 1.52 mb).
For more information on TMDLs, contact WSDOT's TMDL Lead Jana Ratcliff (360)570-6649 or refer to Ecology's TMDL website.