Lower Iron Creek Culvert Replacement

Project Narrative

The corrugated 41 foot metal culvert on Iron Creek was replaced with a 26 x 35 HS-modular vehicle bridge (DV-VM Bridge).The project was a cooperative effort with the Upper Salmon Basin Watershed Program, the Lemhi Soil and Water Conservation District and Lemhi County Road and Bridge Department. The project implementation was delayed in September 2009 when Idaho Department of Fish and Game Fisheries Biologists documented the presence of ESA-listed Chinook salmon spawning immediately above and below the project site. The presence of Chinook near the project site required revision of the Biological Assessment and the timeline for implementation was changed to summer of 2010.
Extended high flows in Iron Creek during the construction work window resulted in complications with sedimentation release during the dewatering phase of the project.
The replacement of the existing culvert with a bridge resulted in a free-flowing Iron Creek and the elimination of a velocity barrier for certain life stages of anadromous and resident fish. This action resulted in an additional four miles of stream access for ESA-listed fish. Iron Creek is designated as critical habitat and essential fish habitat for Snake River spring/summer ESU Chinook salmon, as well as proposed critical habitat for Columbia River Steelhead trout. The proposed action would allow upstream passage to five miles of high quality spawning and rearing habitat for all life-stages of ESA-listed and resident fish species. This project will also complement the Iron Creek Reconnection project number 019 04 A funded by the 2004 PCSRF grant