A group of citizen scientists started collecting routine water quality data in 2000 to build a baseline understanding of river health in the Upper Gallatin Watershed.

Then, the Montana Department of Environmental Quality (MT DEQ) conducted an intensive study between 2005 and 2010 to identify threats to water quality in the Big Sky area. This study, known as a Total Maximum Daily Load (TMDL) study, evaluated whether streams in the area were healthy enough to meet state water quality standards for recreation, fisheries, public water supply, and other beneficial uses.

Data from 2005 and 2008 suggested that algae growth exceeded state standards on the West Fork and South Fork of the West Fork and was elevated on the Middle Fork of the West Fork. In 2010, the West Fork Watershed TMDL study designated the West Fork, Middle Fork, and South Fork to be impaired or exceeding state standards for nutrients.

Listed Waterbodies, Impairment Causes, and Impaired Beneficial Used in the West Fork Gallatin River Watershed from “The West Fork Gallatin River Watershed Total Maximum Daily Loads (TMDLs) and Framework Watershed Water Quality Improvement Plan”