Steamboat Falls Fishway Design Enhancements
Location: Steamboat Creek, North Fork Umpqua River, Oregon
Client and Partners: The North Fork Umpqua Foundation, US Forest Service, and Oregon Department of Fish and Wildlife (ODFW).
Michael Love & Associates (MLA) conducted a fish passage evaluation and developed design modifications for a 1950’s-era fully-enclosed fishway originally constructed to improve passage for summer and winter steelhead over a 23-foot waterfall on Steamboat Creek in Southern Oregon. A combination of high sediment loads and debris resulted in chronic sedimentation and debris jams that made the fishway inoperable during most years. Poor access allowed routine maintenance only to occur during summer low-flows. MLA services were employed to develop engineering alternatives that would improve year-round passage conditions. Because of the proximity to a heavily used public area, the aesthetics of each alternative was an important consideration in alternative development.
The project involved:
- Identification of migration timing and range of fish passage flows for various races of steelhead,
- Topographic survey of fishway hydraulic controls, including exit orifice, internal weir configuration, irregular crest of bedrock headwater pool, and tailwater controls,
- Geomorphic mapping of bedrock and coordination with the geotechnical engineer to identify opportunities and techniques for bedrock modification to create a bedrock nature-like passageway over the waterfall, and
- Analyses of fishway hydraulics to identify modifications that would reduce sedimentation and debris entrainment and provide passage conditions more in-line with ODFW and National Marine Fisheries Service criteria.
A series of proposed alternatives were developed along with conceptual design drawings and planning-level cost estimates. These were provided in the 2010 project report: Steamboat Falls Fish Passage Evaluation and Alternatives Analysis.
The preferred alternative was implemented by ODFW in 2012 and included modifications to the existing hybrid vertical-slot weirs within the fishway to reduce debris clogging, better process sediment, and increase low-flow water depths for fish. Changes to the exit geometry were also implemented to reduce the amount of sediment and debris entering the fishway, including use of adjustable gates to provide operational flexibility over a range of flows. Other modifications designed by MLA include addition of guidewalls upstream and on the roof of the fishway to remove flow distractions and provide maintenance access higher streamflows. Two summers of monitoring and maintenance have indicated that the proposed modifications have reduced the amount of sediment and debris entering the fishway, allowing steelhead year-round passage through the fishway.