Projects

Hayden Creek Hermits-BLM Habitat Improvement Project – Phases I & II

Hayden Creek is the largest tributary to the Lemhi River, which is a major tributary to the Salmon River. Runoff from Hayden Creek is significant, contributing 30-40% of the Lemhi River’s total annual streamflow. It remains a productive spawning stream for wild steelhead and Chinook salmon with as much as half of all Lemhi basin redds occurring between the mouth and the East Fork Hayden Creek. Winter and summer rearing habitat are lacking in lower Hayden Creek due to channel modification and the disruption of natural inputs that create geomorphic complexity (mainly removal of woody debris). The 1.2-mile project reach is located on private property and public land managed by the U.S. Bureau of Land Management (BLM). Hayden Creek is a naturally confined stream that is incised relative to average flood stage. Thus, floodplain inundation and instream hydraulic variability are driven by stream inputs (instead of channel morphology), such as woody debris, that decreases the energy gradient and increases local water elevations.

The goal of the project was to enhance existing spawning habitat and increase the amount of connectivity of microhabitats crucial for juvenile Chinook salmon and steelhead rearing by introducing unanchored, loose, large woody debris material and anchored log structures to the system. The addition of wood structures provides immediate instream habitat, cover, gravel retention/sorting, and velocity, depth, and water surface variability.

Rio ASE provided concept development to final designs (construction-ready drawings, specifications, cost estimates, and bid documents), 2D hydraulic modeling, basis of design reporting, permitting support, and construction observation for this project.

Plan and section views of wood structure design detail.