Beaver Creek Culvert Replacement Design

Develop designs to replace the culvert under Pine Creek road where it crosses Beaver Creek with an arch culvert that would re-establish anadromy to an additional 1.5 miles of stream habitat. Allowing fish passage at impassable stream crossings is a priority action, as identified in the SONCC Recovery Plan (http://www.nmfs.noaa.gov/pr/recovery/plans/cohosalmon_soncc.pdf). Spawning habitat is available above but not below the culvert – below the culvert steep gradients and inherently unstable channel banks confine the stream to a series of small, plunging cascades. The culvert, an 8-foot diameter corrugated metal pipe, has been undercut at the downstream end, leaving an overhanging (‘shotgun’) section where water plunges onto semi-angular boulders, providing no jump pool whatsoever. Below this blockage, perennial, cool, surface flows provide direct access to Trinity River mainstem throughout low water periods, affording some 200 yards of stream useful as thermal refuge for non-natal SONCC and other native fishes. Habitat above the culvert is suitable for salmonids; Hoopa Tribal Fisheries have captured age 0+ and 1+ Oncorhynchus mykiss above the culvert via electrofishing, but have not identified SONCC Coho above the culvert, as anadromy is blocked. This project involves coordination with the Humboldt County Public Works Department, NOAA Fisheries, and Hoopa Valley Tribal Government Roads Department to scope design the culvert retrofit.

Address fine sediment impacts identified in the 2017 Mill Creek Watershed Assessment funded by FRGP. SONCC in the lower Trinity River are identified in the Recovery Plan as being at high risk of extinction. Restoration of tributary habitat for both natal and non-natal SONCC is therefore of great importance. Lower reaches of Beaver Creek provide year-round flows of cool water into the Trinity River. Both non-natal and natal juvenile SONCC as well as adults will be afforded free access to an additional 1.5 miles of suitable habitat consisting of pools, riffles and runs. Therefore, this project is expected to support increases in survival and growth of Coho as well as the other native anadromous salmonids. Hoopa has started up a conservation hatchery for Coho Salmon on the HVT fisheries campus. If Coho do not stray up this stream after so many years of exclusion by the crossing, it would be eligible for out planting from the conservation hatchery to kick start the population in that stream.