Building a Drought Early Warning System for Cold-Water Fisheries Management Across the Northern Rocky Mountains

Extreme droughts are becoming more frequent and severe, threatening freshwater ecosystems and the services they provide. Drought reduces streamflows, increases water temperatures, and stresses trout populations, leading to declines in survival and production. This is particularly concerning for cold-water trout fisheries that have enormous ecological, cultural, and economic importance across the Western United States. 

To address these challenges, scientists at the U.S. Geological Survey (USGS), Montana State University, and Montana Fish, Wildlife & Parks, with support from the NOAA National Integrated Drought Information System, developed Drought Early Warning Systems (DEWS) for Montana's popular trout rivers. This project used long-term trout monitoring data to understand how extreme drought conditions, including low river levels and warm water temperatures, have impacted Montana’s popular trout fisheries over the past 30 years. 

The final product is a first-of-a-kind drought early warning system that can be used by managers and the public to prepare, mitigate, and manage valuable freshwater fisheries. This information is publicly available through an interactive web tool, TroutCast, which launched on June 1, 2026.

This research was funded by NIDIS through the FY 2022 Coping with Drought Competition – Ecological Drought. For more information, view the U.S. Geological Survey project web page or contact Britt Parker (britt.parker@noaa.gov).