North River Culvert Replacement

The North River Fish Barrier Culvert Correction – 8.3 is on an unnamed tributary to the North River at road milepost 8.3. The culvert is located at the mouth of the creek, with the culvert outlet at the river’s edge. The stream is over 1 mile long, has a bankfull width of 8 feet, and good riparian cover of mature alder backed with 20 year old conifer. The existing culvert was steel, 3 feet in diameter, 80 feet long, with a 5% slope and 7 foot outfall drop to the river. It is a total passage barrier to all fish and aquatic life forms based on WDFW fish passage criteria. Stream substrate is fine sediment in the lower portion due to numerous beaver dams; large woody debris is abundant. The upper watershed above the beaver dams had some low quality spawning gravel. The watershed is managed forestlands. Stream habitat would support coho and cutthroat trout spawning and rearing as well as potential rearing for other juvenile salmonid species. This type of off-channel habitat is a limiting factor for the North River. The correction would be a 3 gage, multi-plate round culvert, 96 feet long and 15 feet wide, installed using the WDFW zero slope design. Stream gradient would be 3.9% through the culvert. This gradient would be maintained for 240 feet upstream using LWD and rock weir regrade controls. Gravel placement and revegetation would completed the project. The engineering has been completed in cooperation with WDFW engineers.


Posted on

February 25, 2020