Woodcock Creek & Grimm Road Fish-Passage Project

Prior to the project, a 10’ wide box culvert in Clackamas County between Colton and the City of Molalla carried Woodcock Creek under Grimm Road. Woodcock Creek is a tributary of Milk Creek, which flows into the Molalla River. Woodcock Creek drains 12.8 square miles and contains 25.2 miles of anadromous fish habitat. The previous culvert was the remaining complete fish passage barrier on Woodcock Creek and prohibited access to 11 miles or more of high-quality habitat. The previous culvert was undersized and was perched approximately 16” on the outfall end, making it a partial or complete barrier to fish passage. Additionally, it had a flat concrete floor which created a sheet flow with an average depth of two inches at lower flows and with extreme velocities at higher flows. Upstream aggradation and excessive erosion downstream were constant problems due to the constricting nature of the narrow culvert. This project replaced that culvert with a precast modular bridge, 1.5 times the bank-full stream width. The new bridge will reduce erosion, allow natural streambed processes to occur, and provide additional more high-quality spawning and rearing habitat for ESA threatened upper Willamette DPS winter steelhead, upper Willamette DPS spring Chinook, coho, and cutthroat. Reporting of channel grading for streambed restoration was incorrectly omitted when the project was proposed and was implemented. Also, much needed habitat complexity was added by installing large wood channel-margin logjams and boulders. Riparian planting and plant removal were reported at proposed but these actions were limited to areas disturbed by project activities and therefore are omitted at actual. Partners include Molalla River Watch (MRW), ODFW, and Clackamas County Department of Transportation & Development (CCDTD). CCDTD provided survey work, engineered design development of the preferred alternative, additional construction funding, Utility coordination, public outreach, construction oversight and project reporting. MRW will replant the associated riparian zone in Spring/Summer 2025.

Molalla River Watch, CCDTD, and ODFW have categorized the Grimm Road crossing on Woodcock Creek in the Molalla River Watershed as a priority culvert replacement to restore fish passage to upstream habitats for all aquatic species. This project will replace a perched, concrete-bottom undersized culvert that is a fish passage barrier with a modular bridge that is 1.5 times bank-full width. The proposed project will also install several pieces of large-wood, boulders, native plantings, and vegetated swales. These actions will increase habitat complexity and diversity and will restore natural stream processes to this reach of Woodcock Creek. This project will help to restore the hydrologic processes that will increase habitat area, complexity and quality for ESA threatened Upper Willamette ESU spring Chinook, threatened upper Willamette DPS listed winter steelhead, along with non-ESA-listed coho, and native cutthroat trout. With technical assistance from Clackamas SWCD’s riparian specialist, we plan to replant the riparian area adjacent to the project site with trees that will shade the stream, prevent erosion, reduce fine sediment loads, filter road runoff, and eventually provide nutrients and natural wood recruitment to improve stream complexity. Once the fish passage impediment at Grimm Road is removed, access to the upstream forested areas with cooler water temperatures will provide high-quality spawning and rearing habitat. Those properties include Port Blakely, immediately upstream of the project site, and Ramsdell at the headwaters of Woodcock Creek, which are managed forests with commitments to improve fish habitat quality.