Montana's TMDL Development Priority Areas

Within Montana, TMDLs have been developed in more than 50 different project areas, *some representing successful completion of a 2011 amended judgment to a TMDL lawsuit originally filed in 1999. Yet there are many remaining areas that contain impaired waterbody - pollutant combinations that still require TMDL development, all of which are identified on the state's 303(d) list. To address the remaining development requirements, DEQ identifies TMDL development priority areas, discussed below.* TMDL project areas are often referred to as water quality planning project areas because of the combined activities of a DEQ monitoring and assessment phase, followed by the TMDL development phase. In watersheds with completed TMDLs, DEQ's nonpoint source program personnel provide support to help implement the TMDLs.

* All final TMDL documents can be found on the Final TMDL Documents page
* To see an interactive map of all project areas with completed TMDLs, including priority areas, see our TMDL Project Area Status Map page
* To see a map of just the TMDL priority areas, click here

In prioritizing watersheds for TMDL development, DEQ, in consultation with the statewide TMDL advisory group, applies a process that identifies priority factors consistent with state law. The factors with most influence include those linked to the likelihood that local stakeholders will pursue TMDL implementation; the ability to improve coordination among water quality programs; and the recreational, economic and aesthetic importance of the waterbodies in a watershed. The resulting priority watersheds are where DEQ focuses resources toward monitoring and assessing water quality, and subsequently developing TMDLs.

The water quality planning process that includes TMDL development may take two to five years to complete.  TMDL projects normally address multiple types of pollutant impairment causes, organized into pollutant groups.  The most common pollutant groups in Montana are: sediment, nutrients, metals, temperature, pathogens, and salinity.  Each pollutant group can have unique water quality standards, sources, assessment methods, sampling protocols, corrective measures, and impacts to designated beneficial uses.

Priority Area Information

Below is a list of the Montana DEQ Water Quality Planning/TMDL Priority Areas along with some general project information and priority rationale. The list is organized first by those areas scheduled for TMDL completion by 2017, followed by those areas scheduled for TMDL completion by 2022. This scheduling approach is consistent with EPA's new 303(d) vision which requires states to identify their priority areas for TMDL completion by the end of Calendar Year 2022. Note that DEQ may adjust TMDL development priorities based on new information and proposed activities throughout Montana. Project area status and DEQ contact information are provided on the TMDL Project Status page.

Priority Areas Scheduled for Completion by End of Calendar Year 2017

Click site for more information

Number of TMDLs Planned

1 (iron)


Priority Rationale

High level of local interest regarding a proposed coal mine and potential impacts to irrigation water quality

Internal coordination between DEQ water quality programs

Accelerated TMDL completion required because of pending MPDES permit application

Significant TMDL support activities completed; TMDL development in progress


Additional Consideration

Salinity is also identified as a cause of impairment on Otter Creek. Site specific salinity standards are under development for Otter Creek. These standards could negate salinity TMDL development requirements.


Project Website

Otter Creek TMDL Project Website

Number of TMDLs Planned

31 (may vary dependent upon assessment results)

Pollutant groups include sediment, nutrients, metals, temperature, pathogens


Priority Rationale

High level of local interest in water quality protection and TMDL implementation

Important economic resource (fishing, ranching, tourism)

Most monitoring and assessment completed; TMDL development in progress


Additional Consideration

Water quality standards work in progress to address high natural levels of arsenic in the Madison River and some tributaries.

Number of TMDLs Planned

4 (may vary dependent upon monitoring & assessment results)

Pollutant Groups include nutrients, metals, pathogens; sediment is also being evaluated


Priority Rationale

Internal coordination between DEQ water quality programs

High level of interest over proposed copper mine and potential water quality impacts

Important tributary to Smith River with high economic resource value (fishing, tourism)

Some monitoring complete, significant monitoring, assessment, and TMDL source assessment work planned during 2015


Project Website

Sheep Creek TMDL Project Website

Number of TMDLs Planned

33 (may vary dependent upon monitoring & assessment results)

Pollutant groups include nutrients, metals, and temperature


Priority Rationale

High level of local interest in implementation (There are 22 completed TMDLs in this watershed. Completing the remaining TMDLs will facilitate a more holistic approach for local stakeholder watershed restoration planning)

Ability to address large number of TMDLs within a reasonable timeframe to maintain a minimum TMDL development pace

Important economic resource (fishing, ranching, tourism)


Project Website

Beaverhead Watershed TMDL Project Website

Priority Areas Scheduled for Completion between 2017 and 2022

Number of TMDLs Planned

33 (may vary dependent upon monitoring & assessment results)

Pollutant groups include nutrients, metals, salinity, and sediment


Priority Rationale

Local watershed group with interest in water quality protection, including irrigation water quality protection

Internal coordination between DEQ water quality programs including wetlands program and external coordination with flood recovery activities


Project Website

Musselshell Watershed TMDL Project Website

Number of TMDLs Planned

2 (Phase II of nutrient TMDLs)


Priority Rationale

Important economic resource (fishing, tourism)

Internal coordination between DEQ water quality programs; opportunity to address potential future growth concerns

Previous commitment to complete Phase II work

Significant Phase II TMDL support activities completed, including watershed modeling


Additional Consideration

Numeric nutrient water quality standards work in progress for Flathead Lake. This could affect TMDL development.


Flathead Lake Project Websites

Flathead Lake Watershed TMDL Development Project Website

Flathead Nutrient Standards Development Project Website

Number of TMDLs Planned

40 (may vary dependent upon monitoring & assessment results)

Pollutant groups include nutrients, metals, sediment, and temperature


Priority Rationale

A variety of local stakeholders with interest in water quality protection activities

Ability to address large number of TMDLs within a reasonable timeframe to maintain a minimum TMDL development pace.

High native fish resource value.

Number of TMDLs Planned
  • 35 (may vary dependent upon monitoring & assessment results)
  • Pollutant groups include nutrients, metals, salinity and sediment

Priority Rationale
  • Significant number of permitted discharges; opportunity for increased coordination between DEQ surface discharge permitting program and TMDL development
  • Opportunity for increased coordination with local stakeholders working on water quality protection
  • Important resource water with increased population growth along the river corridor

Additional Consideration
  • Ongoing water quality standards projects involve site specific numeric nutrient standards development and evaluation of naturally high arsenic levels.

Number of TMDLs Planned

To be determined after water quality standards and assessment activities are completed; based on these results it is possible that no TMDL development will be required


Priority Rationale

Industrial activity with associated water quality concerns


Additional Consideration

Salinity levels could be naturally elevated above existing numeric standards; salinity modeling initiated with potential to inform water quality standards evaluation