A Water Year in Review

Water is an essential resource throughout the Gallatin watershed. Whether you use it for irrigation, fishing, skiing, or even just washing dishes, it’s crucial to understand how much water is stored and moves within the watershed each year. To track this, hydrologists have established a “water year,” a 12-month period that runs from October 1st to September 30th, which most accurately captures precipitation totals. This timeframe allows for the inclusion of winter snow accumulation as well as spring and summer rainfall, providing a complete picture of the water supply throughout the year.

To estimate water levels in the watershed, hydrologists use various measurement methods. From October through June, Snow Water Equivalent (SWE) is the primary metric, reflecting the snowpack’s contribution to the watershed. The Gallatin Watershed snowpack is represented by averaging data from seven SNOTEL sites.  At each site, data is recorded for snowfall, precipitation, and temperature. From June to September, streamflow and reservoir levels become the key indicators for assessing water levels. Additionally, soil moisture and air temperature are used to evaluate drought conditions, helping agencies and irrigators make informed management decisions to maintain the health and resilience of the Gallatin ecosystem.

Review of the 2024 Water Year

Fall 2023 – Winter 2024
Snow accumulation from October to March was notably lower than the previous year. SWE measurements, based on a 30-year average, revealed consistently below-median snowpack levels. By the end of March, the Gallatin River drainage had received 17.2 inches of precipitation, slightly below average, compared to 23.5 inches in 2023.

Spring 2024
By April, Gallatin County was experiencing moderate to severe drought conditions. Precipitation in April and June was significantly lower than May, though spring snowstorms provided some relief. Despite this, snowpack levels remained below normal in higher elevations, creating a deficit to overcome. Snowmelt and runoff peaked during the last week of June, with the Gallatin River at Logan and East Gallatin maintaining normal discharge levels. By the end of June, total precipitation for the year had reached 30.1 inches—6.2 inches less than the previous year.

Summer 2024
While temperatures in Gallatin County were higher than average during the summer months, consistent rainfall in August and September helped improve the drought outlook. These late-season rains provided much-needed moisture and stabilized conditions as the water year drew to a close. At the end of September 2024, the Gallatin River watershed received approximately 37.6 inches of precipitation, down from 45.1 inches in 2023. While this marked a below-average water year, the watershed still maintained 93.5% of the 20-year average precipitation. Though dry years are always challenging, they drive irrigators and land managers to adapt and innovate to preserve water in the rivers and protect aquatic ecosystems.

As the new water year begins, we hope for abundant precipitation in the months ahead. According to NOAA, La Niña conditions are expected to influence the 2024-2025 winter, with colder-than-normal temperatures and above-average precipitation from December to February. While this forecast offers hope for improved water conditions, the watershed is still recovering from several years of drought.

Getting Involved with Water Resources in Gallatin County
Getting involved with water resources in Gallatin County is a meaningful way to contribute to environmental conservation and sustainable water management efforts. Start by connecting with local organizations such as the Gallatin River Task Force, Gallatin Watershed Council, and Trout Unlimited, which work to improve water quality, restore habitats, and ensure the long-term health of the watershed. You can participate in volunteer opportunities like river cleanups or join educational programs to deepen your understanding of water management practices. Stay informed about the watershed’s conditions by signing up for email updates or reading the latest reports at gallatincd.org/gallatin-water-supply-outlook-reports. Your involvement can help make a positive impact on the future of Gallatin County’s water resources!