Middle Fork Coquille Falls Project: Improving Fish Passage Through Innovative Design and Implementation

Tackling Fish Passage Barriers in Oregon Through Regulatory Knowhow and Engineering Expertise

The Middle Fork Coquille Falls Project targeted a critical barrier to fish passage on the Middle Fork Coquille River in Oregon, where steep hillsides and the proximity of Oregon Highway 42 created formidable challenges. Beginning in 2022, River Design Group (RDG), now a part of SWCA, pioneered engineering strategies to overcome site access constraints, restore the channel to improve passage conditions, and meet regulatory requirements. After SWCA acquired RDG in 2024, our combined team provided on-the-ground technical expertise during the project’s implementation phase to ensure design intent compliance; driving pre-construction coordination, construction services, and successful closeout.

The need to restore fish passage at this site was urgent. Physical channel conditions, including large boulders within the channel, demanded immediate action. SWCA’s involvement ensured cohesive project partner coordination, creative engineering design, and high-quality deliverables to move the project from design to reality.

Heavy earthwork equipment entering the Middle Fork Coquille River canyon channel.

Overcoming Logistical Obstacles

Post-project channel conditions showing a gravel low-flow channel with strategically exposed boulders to enhance hydraulic complexity.

The Falls location between steep terrain and the adjacent highway made access and in-channel work exceptionally complex. SWCA’s team navigated stringent environmental regulations and applied best management practices to safeguard the river’s ecosystem throughout construction by proposing work area isolation measures, site access methodologies, and construction techniques. These challenges mirrored those faced by clients working in sensitive habitats, where ecological stewardship and regulatory compliance are essential.

The project was part of a holistic effort to improve fish passage, habitat connectivity, and habitat quality in the Middle Fork Coquille watershed in partnership with the Coquille Watershed Association (CoqWA) and Oregon Department of Fish and Wildlife (ODFW). Eliminating the anthropogenic fish passage barrier allowed for the restoration of approximately 9.5 miles of spawning and rearing habitat for Oregon Coast coho salmon, Chinook salmon, winter steelhead, and pacific lamprey. The project will also benefit populations of coastal cutthroat and freshwater mussels that reside in the Coquille sub-basin.

Delivering Results Through Expert Coordination

SWCA provided construction administration services for the project, including pre-construction planning, contractor submittal review, project stakeout, and onsite construction observations ensuring all work conformed to the project design intent. Given the project’s complexity, including selective boulder reduction (jack hammering), relocation, and removal to establish a passage channel, SWCA facilitated near-daily coordination with project partners and the contractor to maintain alignment with design objectives.

Throughout construction (August to September 2025), SWCA conducted multiple site visits to observe key milestones in the construction sequence and document progress. The final as-built survey with aerial imagery provided stakeholders with detailed, reliable documentation of final site conditions. SWCA staff built upon an 8-year relationship with the project partners, allowing the team to feel confident in the technical input provided by our engineers.

Project partners (Oregon Department of Fish and Wildlife, Coquille Watershed Association, SWCA, and Blue Ridge Timber Cutting) accessing site conditions during the pre-construction meeting.

Enhancing Fish Passage and Ecosystem Health

SWCA staff conducting a total station as-built bathymetric survey of the newly developed passage channel.

Through Sound Science, Creative Solutions, and a commitment to technical excellence, the Middle Fork Coquille Falls Project has significantly improved fish passage and advanced the broader goals of ecological restoration in the watershed. SWCA’s transparent and collaborative oversight, from conceptual design through post-construction documentation, ensured that every project milestone was met with precision and accountability. Our rigorous approach not only satisfied regulatory requirements but also instilled confidence among project partners. The success of the Middle Fork Coquille Falls Project stands as a testament to what can be achieved through expert coordination, innovative implementation, and a shared vision for healthy, connected river systems and reflects SWCA’s dedication to delivering lasting environmental benefits while meeting the needs of partners and stakeholders.