• If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.

  • You already know Dokkio is an AI-powered assistant to organize & manage your digital files & messages. Very soon, Dokkio will support Outlook as well as One Drive. Check it out today!


Welcome to the Bitterroot River Watershed TMDL Projects

Page history last edited by Christina Staten 4 years, 4 months ago Saved with comment

Project Overview

TMDL Outreach      Completed TMDLs 

Bitterroot Nonpoint Source Focus Watershed Homepage


The TMDL Process in the Bitterroot River Watershed 


The Bitterroot River watershed is an area of over 2,820 square miles.  Water flows from its headwaters of the East and West Forks of the Bitterroot River to its confluence with the Clark Fork River near Missoula.  Water quality problems are occurring in many rivers and streams in the Bitterroot Valley.

Clean water is essential for many uses including healthy fisheries, safe drinking water, farming and recreation.  The economic and environmental costs of poor water quality can be substantial, particularly in an area renowned for its natural amenities. 


Water quality standards have been set to ensure healthy and productive systems for the wellbeing of the natural environment and the people who live, work, and play in Montana. The Montana Department of Environmental Quality (DEQ) assesses the waters, and for those waters not meeting the state standards, develops framework strategies that will lead to the achievement of those standards. This process is known as TMDL development.


In Montana, the geographic scale for the TMDL process is at the watershed level since most pollutants are contributed over a large area from nonpoint sources.  The Bitterroot watershed is divided into three separate TMDL planning areas (TPA): The Bitterroot Headwaters TPA, the Upper Lolo TPA, and the Bitterroot TPA. TMDL development in currently taking place in the Bitterroot TPA; all TMDLs have been completed in the Upper Lolo and Bitterroot Headwaters TPAs. See the Project Overview page for a map of all three planning areas.


DEQ has identified the following primary cause groups as impairments to water quality in the Bitterroot: metals, nutrients (nitrogen and phosphorus), siltation/sediment, and thermal modification (temperature).


The TMDL planning process in the Bitterroot watershed incorporates a combination of a watershed scale hydrologic model and on-the-ground field efforts to further identify and quantify pollutant contributions from all significant sources. Used in combination, these methods will yield the best available picture of the current water quality conditions and reasons for problems.


The result of this process is individual TMDLs for all impaired rivers and streams, plus a comprehensive understanding of how pollutant inputs are affecting the Bitterroot River. Completed TMDL documents give local stakeholders a clear idea of where the problems are, what causes them, and what it will take to improve water quality to preserve existing uses of the water.



Please use the quick links in the top right corner of this page to navigate to other Bitterroot TMDL project pages.