sonoma County, CA
Mill Creek Dam Fish Passage
Project Details
This project removed a major fish passage barrier on Mill Creek, opening 11.2 miles of prime spawning and rearing habitat for endangered coho salmon and steelhead trout. The innovative design balanced residential needs with fish passage requirements, creating a natural-looking solution that was recognized with a distinguished engineering award.
Location: Sonoma County, CA
Client: Private Landowner
Located on a Russian River tributary harboring excellent salmonid habitat, Mill Creek's 5-foot concrete dam blocked fish migration for decades. The National Marine Fisheries Service identified it as "the highest priority barrier within the Russian River coho population." PCI partnered with Trout Unlimited to design and implement an innovative solution despite challenging site constraints in residential backyards. The design created a side channel with modest grade, lowered the dam height, and constructed roughened boulder channels for fish passage. Funding partners included NOAA Restoration Center, Sonoma County Water Agency, and California Department of Fish and Wildlife. Post-construction monitoring confirmed success when coho salmon were documented spawning upstream just two months after completion.
project goals
Restore fish passage to 11.2 miles of prime coho and steelhead habitat
Create natural-looking solution compatible with residential setting and property owner needs
Engineer design accommodating both adult and juvenile salmonid migration requirements
benefits
Opened critical spawning grounds for endangered Russian River coho salmon population
Successfully balanced ecological restoration with residential needs and aesthetic considerations
Created award-winning design recognized for engineering excellence in fish passage
PARTNERSHIPS
Trout Unlimited
NOAA Restoration Center
Sonoma County Water Agency
California Department of Fish and Wildlife
UC Cooperative Extension
California Sea Grant
PROJECT MAP
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