Cooper Mill Fish Passage Improvement Design

Location of Project: Downstream Project Extent –
40.55923000 : -124.05789000 – Cooper Mill and Yager Creek confluence, Map

COMPLETED: The objective of this project is to develop preliminary site characterizations that will guide the basis of design report, alternatives analysis, and final engineered designs for the Cooper Mill Fish Passage Improvement Design Project (CMFPP).

Forum Funding Received: $87,230

Description of Project, including deliverables: The objective of the project is to develop 100% designs for two fish barrier locations on Cooper Mill Creek that will lead to improved fish passage for all salmonid life stages. Cooper Mill Creek is an important anadromous fish-bearing tributary of Yager Creek, a major tributary to the Van Duzen River. Cooper Mill contains 3.0 miles of anadromous stream and opportunities to provide summer and winter cold-water refugia habit for three salmon species. The proposed project area is located on Humboldt Redwood Company property (HRC), and the proposed project team includes TU, HRC, and Pacific Watershed Associates (PWA).

The designs will focus on improving fish migration for all life cycles of coho salmon and steelhead trout during all seasons. The project area extends from the first barrier, located at the confluence of Cooper Mill Creek and Yager Creek, upstream about 5 miles to the second barrier, a remnant channel spaninng concrete weir associated with an abandoned fish hatchery.  The design process will include a thorough site assessment of existing conditions, an analysis of design alternatives, and final designs for up to two future restoration projects.

Cooper Mill Creek suffers from legacy impacts of industrial timber practices, including channelization and levee development, irregular large debris accumulations, rip rap bank protection, and other infrastructure located in proximity to the stream. The proposed objective is to develop 100% designs that are focused  on enhancing instream habitat and improving fish migration for all life cycles of Coho and other salmonids. The design process will include an analysis of alternatives that address: 1) the constructed boulder step weir located at a debris accumulation at the confluence with Yager Creek; 2) the concrete weir upstream (PAD #); 3) historic channelization and poor instream habitat complexity; and 4) appropriate locations and configurations of instream habitat structures between the two barrier locations.

This project will improve access for natal and non-natal salmon species to high priorty refugia habitat during extreme water velocity and temperature events in the lower Yager Creek basin.

This barrier is a high priority project:

    • Barrier is listed in a key restoration plan for the region
    • Local knowledge/conversation with local representatives

The name(s) of the recovery plans and the specific task that name this barrier as a high priority: 

    • National Marine Fisheries Service, 2016, Final Coastal Multispecies Recovery Plan, National Marine Fisheries Service, Santa Rosa, California
    • SONCC-LEVR. Improve access – Remove Sediment Barriers – Remove alluvial deposits, construct low flow channels, or reduce stream gradient to provide fish passage at all life stages
    • CDFG, 2004, Recovery Strategy for California Coho Salmon, CDFG, Sacramento, CA
    • ER-VD-01- Develop a plan to restore and maintain tributary and mainstem habitat connectivity where low flow or sediment aggradation is restricting coho salmon passage.

The California Fish Passage Forum has nine overall objectives. This project will help address the following objectives: 

    • 1. Remediate barriers to effective fish migration.
    • 3. Identify, assess and prioritize the removal of fish passage barriers.
    • 9. Implement education and outreach activities, targeting both the general public and fish passage practitioners.

The anadromous fish species that will benefit from the project: 

    • Coho salmon
    • Chinook salmon
    • Steelhead/rainbow trout

The miles of stream opened as a result of implementing the project: 1.7

National Conservation Strategies that will be addressed by the project: 

    • 1. Protect intact and healthy waters.
    • 2. Restore hydrologic conditions for fish.
    • 3. Reconnect fragmented fish habitats.

USFWS Climate Change Strategies that will be addressed by the project: 

    • 3.1 Take conservation action for climate-vulnerable species.
    • 3.2 Promote habitat connectivity and integrity.
    • 3.5 Conserve coastal and marine resources.

The project will design and eventually implement proactive conservation measures Coho Salmon and steelhead trout which are both listed under CA state and Federal ESA. The project intends to restore fish passage at two identified barriers and to improve instream habitat conditions between those two locations . The project will connect fragmented habitats within Yager Creek and Cooper Mill Creek which are identified as high priority core recovery watersheds for threatened SONC Coho Salmon. The project will address climate change by providing access to cold perennial water in the summer and by providing refugia during intense storm events.  These two climate conditions, prolonged drought and intense storm events, are both predicted to occur more frequently in a changing climate.

Fishery enhancement: Recreational steelhead fishing does occur in the Van Duzen River basin.  The project would assist in providing access to spawning and rearing habitat for steelhead trout and Coho Salmon (a former commercial fishery).  The long term results of the project are intended to assist with restoring native salmon populations to their recovery targets.  If accomplished both commercial and recreational fishing opportunities would be enhanced.