South Fork of the Boise River Flows to Increase Significantly


  • Outdoor Exchange / Boise River Canyon Shuttle Service
When the Pony and Elk Complex fires burned through the hillsides along the South Fork of the Boise River last summer, it had a significant impact on fish habitat. Intense rain from thunderstorms and large doses of snowmelt then saturated the exposed soils, triggering several large mudslides to flow into the river—causing damage to roads and stream habitats.

In an attempt to restore fish habitat, water managers plan to greatly increase flows in the South Fork of the Boise River next week. The Bureau of Reclamation will increase river volume from Anderson Ranch Reservoir by 400 cubic feet per second (cfs) on Aug. 18 and 300 more cfs on Aug. 19. The flow will jump from 1,700 cfs currently to 2,400 cfs and remain that way for eight days. The water will drop back down to 1,700 by Aug. 29, according to a news release from the Idaho Department of Fish and Game.

This high water will help recover fish habitat in one of Southwest Idaho's most important trout streams. It both supports critical habitat for migratory bull trout and serves as a premier fishery for rainbow trout. But large volumes of sediment and debris can wreak havoc on fish habitat. After recent thunderstorms flooded the South Fork of the Salmon River with sediment, it killed some 1,200 Chinook salmon

The plan to release more water mimics typical spring runoff, which helps restore fish habitat in rivers after severe fire seasons. Staff from the U.S. Forest Service, the U.S. Bureau of Reclamation, the University of Idaho, Trout Unlimited and the Idaho Department of Fish and Game worked together to develop this strategy.