Flathead TMDL Project Overview
Draft Document Contacts Project Outreach Nutrient TMDLs Sediment & Temperature TMDLs
Welcome to the Flathead TMDL Project
Flathead Lake drains an area of six million acres stretching from its northern reaches in Canada to the Salish-Kootenai tribal lands and the Swan. Timber, agriculture, tourism, hunting, fishing and a rapidly growing urban and suburban population all depend on clear, cool waters in the rivers, lakes and streams in the Flathead Lake watershed.
Water quality standards have been set to ensure healthy and productive systems for the well being 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 improvement plans that will lead to the achievement of those standards. This process is known as total maximum daily load (TMDL) development.
DEQ has identified the following primary cause groups as impairments to water quality in the Flathead Lake watershed: nutrients (nitrogen and phosphorus), sediment, PCBs, metals (arsenic, mercury) and thermal modification (temperature).
The TMDL planning process in the Flathead Lake watershed incorporates a combination of a watershed-scale hydrologic model, lake response models, 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 current effort addresses two related issues: developing TMDLs for impaired waters in the Flathead-Stillwater TMDL Planning Area and developing the Phase II nutrient allocations for Flathead Lake. The overall modeling strategy will help address needs for both efforts, while more focused investigation and analysis will be used to address the needs specific to the Flathead-Stillwater area. TMDLs have already been completed for Flathead Lake (Phase I), the Swan River watershed, and the Flathead Headwaters TMDL Planning Area. These documents can be found on the DEQ Final TMDL Documents web page.
The result of this process will be individual TMDLs for all impaired rivers and lakes, plus a comprehensive understanding of how nutrient inputs are affecting Flathead Lake.
Flathead TMDL Project Overview
Draft TMDL Document Project Contacts Project Outreach Nutrient TMDLs Sediment & Temperature TMDLs