Success of Instream Habitat Structures After a 50-Year Flood in Gold Creek, Montana

Gold Creek, in western Montana, lost complexity and diversity of fish habitat following riparian logging activities, removal of instream wood, and subsequent scouring. In the 4.8-km study area, the stream was almost totally void of large woody debris (4.2 pieces/km) and associated pools (1.3 pools/km). We constructed 66 structures made of natural materials (rock and wood) that resulted in 61 new pools in the study area in an attempt to restore salmonid habitat in the fall of 1996. An estimated 50-year recurrence interval flood occurred in the following spring. Of the original 66 structures, 55 (85%) remained intact and stable. Laterally confined reaches retained significantly more pools than laterally extended reaches. Owing to a history of anthropogenic impacts in forested streams in the intermountain west, restoration efforts are needed. If instream structures are tailored to specific morphologic channel types, fish habitat restoration can be successful and withstand major floods.