Reno, Nevada
With the goal of enhancing fish habitat and aesthetics within the Truckee River, 7Q10 examined the potential effects of boulder emplacement within the section of the stream channel between the Sierra Street and Virginia Street bridges, adjacent to the Reno City Redevelopment Truckee River walk. Fish habitat was poor because this section of the Truckee River flowed fairly uniformly through the 125-foot stretch, without the boulder pools and eddies needed to produce variability. During high flow periods, few pools and eddies existed for fish to rest and feed and during low flow periods, shallow water warmed and failed to hold the oxygen necessary for fish survival.
7Q10 used the HEC-2 analysis to model pre- and post-project river flood profiles to determine potential flooding due to “random” boulder placement versus the creation of riffle pools. The HEC-2 analysis showed that the creation of riffle pools would increase the 100-year flood stage by 0.19 feet more than random boulder placement. 7Q10 recommended that 10 to 15 boulders be placed randomly in the deepest part of the stream channel (the “thalweg”) in an S-shaped pattern and/or in small groups. The design would enable pool formation and variability, maximize the creation of fish habitat by avoiding pool overlap, potentially decrease water temperature, and create a more natural and aesthetic river scene. As a result of our recommendations, scour pools have been created increasing a healthy fish habitat within the downtown Truckee River corridor.