State of the Gallatin
To the uninformed angler, leisurely casting dry flies to eagerly awaiting cutthroat, the Gallatin may seem like a healthy waterway.
2023 Gallatin River Report
2023 Data Results for Nutrients and Algae
Below state standards for nitrogen and phosphorus.
High in phosphorus (geology related) but not subject to typical water quality standards.
Above water quality standards for nitrogen at various points throughout the summer.
What Causes Algae Blooms?
In 2018, nuisance algae on the Gallatin led to a partnership between the Gallatin River Task Force and Montana DEQ to study water quality. While algae is important for ecosystems, excessive blooms harm river health by degrading water quality, harming aquatic habitats, and deterring recreation. These blooms have multiple causes:
Excess Nitrogen and Phosphorus
While essential for ecosystems, excess nitrogen and phosphorus can be harmful. The West Fork, Middle Fork, and South Fork are impaired by excess nitrogen.
Water Temperature
Seasonal storms and cooler air temperatures in 2023 were influential to lower water temperatures compared to years when algae blooms occurred.
Streamflow
Excessive rainfall in 2023 kept streamflow above average from August through fall, preventing low streamflow which facilitates algae growth by allowing more sunlight to reach the streambed. The rain helped maintain colder water throughout the summer.
2023 Sampling
In 2023, water quality monitoring was conducted by the DEQ along the mainstem Gallatin, and on the nine tributaries shown on the map by the Task Force. There was not a nuisance algae bloom on the mainstem Upper Gallatin, but blooms were observed along the West Fork, South Fork, Taylor Fork and Beaver Creek.
What Was Unique About 2023
In 2023, water quality monitoring was conducted by the DEQ along the mainstem Gallatin, and on the nine tributaries shown on the map by the Task Force. There was not a nuisance algae bloom on the mainstem Upper Gallatin, but blooms were observed along the West Fork, South Fork, Taylor Fork and Beaver Creek.
Algae blooms present in areas testing below state standards for nitrogen + phosphorus
Lower water temperatures
Higher streamflow in late season
Algae present on the West Fork
What's Next?
The next two years of intensive study will complement data from 2023, giving a better understanding of the system and guiding management to protect the river. This will help guide a path forward backed by sound science, but luckily steps are already in motion to ensure the Gallatin runs clean and cold for generations.
Read the article: Hope Outweighs Fear After Montana DEQ Impairment Talk