NE Auburn Creek Restoration Project

Project overview

This project aims to reconnect a perched floodplain tributary to the mainstem Green River channel to restore fish passage and expand rearing and floodplain habitat for juvenile salmon, especially Endangered Species Act (ESA)-listed Chinook salmon. An existing culvert and flapgate at the tributary mouth pose barriers to juvenile use of the nearly 4 miles of upstream channels and will be replaced by modern, fish-passable alternatives.

In addition, a new 725-foot-long channel will be excavated connecting this new culvert to the mainstem to provide not only fish passage to the floodplain but also off-channel rearing and refuge habitat between the mainstem channel and the new culvert and flood gate. A farm access road will be relocated to take it away from the river bank and allow more frequent and direct hydrological connection between the Green River and a 2.7-acre depressional floodplain wetland. This will allow use of the wetland by fish during and after high water events. Moving the road away from the riverbank will also allow widening and enhancement of riparian buffer along 2,000 feet of Green River bank.

The challenge

Rearing habitat for ESA-listed juvenile Chinook salmon is severely limited in the lower Green River which results in many fish migrating to brackish and salt water prematurely. Data indicates that these early-migrating fish rarely return to spawn, so increasing rearing and refuge habitat in the Lower Green River will allow juvenile fish to stay in fresh water for longer and contribute to higher rates of adult salmon returning to spawn.

Juvenile Chinook salmon have been directly observed using and thriving in the NE Auburn Creek system during the rare circumstances that allow them to access the system from the Green River. The NE Auburn Creek Restoration Project will remove a barrier to fish passage (both upstream and downstream) between the Green River and nearly 4 miles of channel in the NE Auburn Creek system, and also restore access to and from from a 2.7-acre riparian wetland. An impassable culvert on NE Auburn Creek at its confluence with the Green River with a nominally functional flapgate that further blocks fish passage will be moved upstream and replaced by a modern, fish-passable culvert and floodgate. A new 725-foot channel will provide passage and off-channel habitat for fish between the Green River and the new culvert. 

These measures will substantially increase the locally available habitat for juvenile salmon and expand available rearing and refuge habitat for ESA-listed Chinook salmon. This will allow them to spend a longer time rearing in fresh water conditions before migrating downstream to salt water, increasing their chances of returning to spawn.

Project timeline

Preliminary Design – Complete
Final Design & Funding Target – December, 2025
Construction Target – Summer, 2026 (contingent on construction funding)

Existing funders

• Washington State Recreation and Conservation Office
• Washington State Salmon Recovery Funding Board
• King County Cooperative Watershed Management Grant (King County Flood Control District) 
• King County Surface Water Management Fees
• King County Parks Levy Open Space River Corridor Grant
• King County Flood Reduction Grant

Project documents

• Preliminary design (14 Mb)
• Instream design checklist (588 Kb)