Rock Creek Confluence Fish Passage Improvement

The City of Vernonia is working on two fish passage improvements within the city limits, at Rock Creek and Bear Creek. Existing infrastructure, namely the sewer system and a culvert in Adams Ave, have created fish passage barriers over the years due to poor construction and/or degradation over time. Within Rock Creek, the barrier is created by the existing sewer pipe and encasing concrete which is exposed during low-flow events and creates an unsuitable jump height for several of the present fish species. Where Bear Creek crosses the Adams Ave ROW, there is a similar sewer impediment which impedes fish passage. In addition to the sewer in Bear Creek, the Adams Ave culvert has degraded and created additional scour pools which add to the problem of allowing fish upstream. This project seeks to remove the existing impediments and provide suitable conditions for fish migration while maintaining the necessary system functionality. Based on ODFW fish surveys, both waterways present migratory, spawning and rearing habitat for Chinook, Coho, Cutthroat Trout, Winter Steelhead, Lamprey, Largescale Suckers, Sculpins, and Crayfish. With this, it is known that different life stages of these species are present throughout the year and the variable flow patterns of the both creeks. Project activities include removing the sewer pipe fish passage barrier, replacing the failing culvert with a bridge, grading the streambed and placing large boulders instream to restore natural channel function, and planting in the riparian area. Project designs have already been created for these improvements through iterative design revisions based on consultation with ODFW and NOAA/NMFS.

Project completion will restore unconditional juvenile/adult salmon passage at the mouth of Rock Creek (30 upstream of confluence with mainstream Nehalem) and the mouth of the adjacent tributary of Bear Creek (500 upstream of the Nehalem on Rock Creek).