| Title: Hollow Tree Watershed sediment reduction and fish passage project
Client: Mendocino Redwood Company and Trout Unlimited
Location: Mendocino County, California
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| Summary: Pacific Watershed Associates was contracted to conduct a sediment source and fish passage barrier inventory and develop mitigation plans to restore anadromous fish habitat
Project Details: The Hollow Tree Creek Implementation Project is part of a cooperative restoration program involving Trout Unlimited, Mendocino Redwood Company and Pacific Watershed Associates. The Hollow Tree Creek watershed is tributary to the South Fork Eel River and provides vital breeding habitat for Coho and Chinook Salmon and Steelhead trout. Many decades of logging and associated road construction in the watershed has degraded fish habitat by contributing excessive fine grained sediment to the stream network and construction of culverted stream crossings resulting in barriers to migratory fish species.
In 2000-2004 Pacific Watershed Associates conducted an upland sediment source assessment and developed a prioritized erosion control and erosion prevention plan. This plan included upgrading and decommissioning roads and the removal of several known fish barriers. Currently Pacific Watershed Associates is executing the third and fourth round of a multi-phase implementation.
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During this process Pacific Watershed Associates:
- Conducted a complete sediment source inventory of the middle and upper Hollow Tree Creek watershed
- Identified all potential fish barriers
- Developed a multi-phase, prioritized implementation plan to upgrade or decommission all roads owned and managed by Mendocino Redwood Company
- Worked with Trout Unlimited to secure state and federal grant funding to implement the project
- Conducted layout and oversight of all road construction activities with the goal of reducing anthropogenic sediment sources and removing fish barriers, and minimizing long term road maintenance costs.
Results: The two completed projects in the watershed (Phase 1 and Phase 2), treated a total of 67 miles of road in the upper and middle portions of the watershed by upgrading 32 miles of road, and decommissioning the other 35 miles of road. The projects have treated a total of 505 sites with an estimated sediment savings of 75,920 yds3 over the next decade. Sites treated included 363 stream crossings, 36 landslides and 106 “other” sites, and a total of 256 stream crossings have been decommissioned. Phase three and four are currently on going and phase five is in the planning stages. Add Statement of overall expected results.
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