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God's Valley Culvert ReplacementsThe God's Valley Creek sub-basin drains 5,100 acres in the North Fork Nehalem River Watershed on Oregon's North Coast. God's Valley Creek is one of the top producers of coho salmon in the Nehalem Bay watershed and is considered a core area by the Oregon Department of Fish and Wildlife (ODFW). The God's Valley Creek mainstem, as well as three of the tributaries included in this project, are designated ODFW High Intrinsic Potential (HIP) areas. God's Valley Road meanders through the valley bottom, crossing over 14 tributaries that drain into God's Valley Creek. The Tillamook Estuaries Partnership (TEP) is addressing a 3.5-mile section of this poorly designed road where high water velocities, culvert plugging, stream overtopping, and road erosion contribute to fish passage barriers and sediment run-off. TEP is also addressing a spur road with similar issues. Key Watershed Issues MP 6.71 Culvert Outlet: 36"x30' CMP Replacement: 10'x5'x30' 3-sided concrete bridge Fourteen tributaries drain into God's Valley Creek after crossing God's Valley Road. This road meanders through the valley bottom on a very low road prism (i.e. minimal fill over the culverts). The low road prism and undersized culverts cause frequent overtopping at the road crossings, resulting in significant sedimentation and erosion problems. Increased levels of fine sediments in spawning areas have been shown to affect the survival of salmon eggs. ODFW Aquatic Inventory (AQI) surveys conducted in the God's Valley sub-basin indicate that while spawning gravels are abundant, fine sediment exceeds desired levels in many areas. The watershed is dominated by Oregon Department of Forestry and private industrial ownership. Although some of the project area has recently been harvested, the proposed restoration project will help expedite recovery of existing fishery resources. ODFW AQI surveys between 2004 and 2005 revealed that the substrate composition on the mainstem of God's Valley Creek above the project area averages 21%. This percentage does not exceed ODFW's benchmarks for fine sediments in riffle habitats (>25% is undesireable). ODFW AQI surveys between 2003 and 2004 on the mainstem of God's Valley Creek in the project area revealed increased sedimentation, with the percentage of fines averaging over 38%. Project Prioritization MP 6.7 Culvert Outlet: 24"x30' concrete Replacement: 8'x5'x30' 3-sided concrete bridge In 2006, watershed partners recognized the need to address water quality impairment and fish passage issues in the God's Valley watershed. The watershed is identified in the Lower Nehalem Watershed Council's (LNWC) 2000 and 2002 Watershed Action Plans. Partners determined that ten of the fourteen culvert crossings under God's Valley Road have fish passage or sedimentation issues. Two culverts were replaced in 2005 and 2007, and a third culvert will be included in a future large wood project. TEP, Tillamook County Public Works, ODFW, Longview Timber Company, and God's Valley Timber Company are partnering to address the remaining seven culverts. Five of the culverts are located under God's Valley Road, which is owned by Tillamook County, and the other two culverts are located under a spur owned by God's Valley Timber Company. In addition to erosion and sedimentation problems, collectively these culverts block fish passage to 2.56 miles of habitat (1.23 coho and cutthroat, 1.33 cutthroat only). The proposed project also offered new opportunities to partner closely with the Tillamook County Public Works Department and two private industrial landowners. The ProblemThe primary cause of the fish passage barrier and sedimentation run-off issues in the God's Valley Watershed is God's Valley Road, which bears a poor road design and undersized culverts. The road was constructed for, and continues to be used for, logging today. TEP is addressing a 3.5-mile section of this road, which crosses 14 tributaries and was cut through the valley bottom at a distance ranging from 200-1000 feet away from God's Valley Creek. A spur road off God's Valley Road has two undersized culverts. Culvert plugging, stream overtopping, and road erosion are frequent along God's Valley Road and the spur road. The table below lists each of the culverts that project partners are addressing and the related watershed concern.
*CMP: Corrugated Metal Pipe SolutionTo remedy the fish passage barriers and sedimentation concerns on the God's Valley Creek tributaries, TEP intends to replace six of the seven culverts listed in the table above. TEP will replace these culverts with six new structures designed by the Tillamook County Public Works Director. Longview Timber Company is replacing the MP 5.9 culvert. All the new structures will meet or exceed the stream's active channel width and will be installed at the stream's gradient. Collectively, the culvert replacements will restore passage to 2.56 miles of salmonid habitat and improve water quality.
*The north end of the seep will be blocked off so it cannot drain into the road ditch. The seep drainage will be rerouted through a newly constructed channel for approximately 280' through the forest to a point 50' upstream of the culvert.  Estimated CostPlanning: $8,000 ScheduleEngineering Designs: Completed PartnersTillamook Estuaries Partnership: lead project manager for six of the culverts |
