Streamflows at Near-Record Lows

By Kristin Legg & Simeon Caskey with the National Park Service

August 7, 2025

Streamflows across the Snake River Headwaters are extremely low for this time of year, with Flagg Ranch experiencing near-record lows.  Since the USGS stream gage was established in 1983, the other notably low-flow year was 2016, when the Berry Fire burned 20,000 acres in Grand Teton National Park and John D. Rockefeller, Jr., Memorial Parkway. Other gaging stations along the upper Snake and its tributaries are following similar low flow patterns. For instance, the Gros Ventre River at Kelly is seeing one of the lowest flows since the gage was established in 1944. At Flagg Ranch, the 2016 and 2025 water years are tracking at or below the 1988 water year, when wildfires burned more than half of Yellowstone.  Although river flows are not indicative of wildfire danger, both are related to drought.

As highlighted in the WyoFile article from July 23, 2025, snowpack was average or in some areas above average this past winter, but early runoff, low soil moisture, and a long dry spell starting in April culminated with the drought conditions we see today.  Since the WyoFile article cited the record low at Flagg Ranch, data from the gaging station have been updated and continue to show near record low flow.

The graphs shown are generated on climateanalyzer.org. Check out the Grand Teton National Park’s “Climate at a Glance”, and/or generate your own graphics for Snotel, USGS gaging stations, or various types of weather stations throughout the Greater Yellowstone Ecosystem and beyond.

The three graphs above show comparisons of the 2016 and current water years against the 1988 water year, and a comparison between the 2016 and current water years.