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 that WSDOT needs to comply with differ in each TMDL.
- 8 TMDLs require WSDOT to comply with permit obligations that address the TMDL pollutant.
- 9 TMDLs require WSDOT to implement actions above and beyond normal permit obligations, as defined in Appendix 3 of the permit.
- 9 TMDLs require WSDOT to apply the 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 the fecal coliform programmatic approach.
WSDOT's Programmatic Approach
The fecal coliform programmatic approach was developed to streamline the development of TMDL implementation plans and ensure WSDOT is required to perform applicable and appropriate actions. The programmatic approach (pdf 191 kb) has been revised to apply to other TMDL pollutants (i.e. temperature, sediment, nutrients). It is applicable when evidence exists that WSDOT is a significant contributor of the pollutant of concern in the watershed. Evidence includes stormwater sampling data or some other actionable information.
WSDOT's programmatic approach includes:
- Inventory of highway discharge locations.
- Illicit discharge detection and elimination (IDDE).
- Visual source identification.
- Identification of maintenance issues (if applicable to the pollutant of concern).
Standard operating procedures (SOPs) describe WSDOT's data collection methods when implementing the programmatic approach in TMDL areas:
Standard Operating Procedure for Data Collection in TMDL Areas (pdf 478 kb)
Reports that summarize findings are submitted to the Department of Ecology for each TMDL that requires WSDOT to implement the programmatic approach. To date, the following reports have been submitted:
Hangman Creek TMDL
Issaquah Creek Basin TMDL
Little Bear Creek TMDL
Swamp Creek Basin TMDL
Stillaguamish River TMDL
Totten/Eld and Skookum Inlets Tributaries TMDL
WSDOT also includes a TMDL implementation summary report as part of the 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.