Columbia River Fisheries Program Office
Pacific Region

Tryon Creek Restoration Monitoring Project

Tryon Creek WatershedTryon Creek is located in southwest Portland and its headwaters are located within those neighborhoods. It flows approximately three miles through this privately owned land before entering Tryon Creek State Natural Area, a 640 acre area of public land, through which the creek flows another three miles. The lower most portion of Tryon Creek flows through public land owned by the City of Lake Oswego and the City of Portland. This portion of the stream is bisected by a culvert that runs under Oregon Hwy 43 and a railroad near the mouth of Tryon Creek (culvert).

Tryon Creek is one of the largest, relatively protected, urban watersheds in Oregon. A number of native species can currently be found in this stream including Oncorhynchus mykiss (resident and anadromous) andcoastal cutthroat trout. Historically, it is thought that Pacific lamprey and coho salmon also utilized this stream. However, the culvert is potentially inhibiting, if not preventing, passage of lampreys and salmonids.

The culvert was constructed in the late 1920s. It is 401 ft long with a drop of nearly 22 ft from top to bottom, resulting in a grade of 4.6%. There are a series of alternating baffles that provide some structure within the culvert, but do not provide adequate holding water for fish attempting to migrate upstream. The culvert is hanging at the lower end approximately eight inches above stream level at base flow. This design likely blocks lamprey migration and hinders salmonid movements upstream through the culvert.

A collaborative project is being implemented by Oregon Department of Transportation, Oregon Department of Fish and Wildlife, Oregon State Parks, National Marine Fisheries Service, Cities of Portland and Lake Oswego, Friends of Tryon Creek, Tryon Creek Watershed Council, National Fish and Wildlife Foundation and U.S. Fish and Wildlife Service to improve passage conditions for anadromous fish migrating into Tryon Creek. A replacement project for the culvert will occur in two phases. The initial phase will retrofit the existing culvert with a new baffle system and provide some habitat restoration to the stream below the culvert to be more conducive to lamprey and salmonid holding and passage. The second phase will provide and implement a long-term solution to replace the existing culvert. Solutions currently being considered include a much larger culvert and a bridge.

The assessment and monitoring project that is being led by the U.S. Fish and Wildlife Service is being conducted in conjunction with the culvert replacement project. This project is being conducted in three phases: 1) pre-assessment and monitoring prior to the initial phase of culvert improvement; 2) post-assessment and monitoring subsequent to the initial phase and preassessment and monitoring prior to the second phase of culvert replacement; 3) post-assessment and monitoring subsequent to the completed culvert replacement project.

Tryon Creek Restoration Monitoring Project: 2008 Progress Report
OPB article - Threatened Fish Return to Tryon Creek, March 24, 2008
OPB Tryon Creek Audio, March 24, 2008 (mp3 4.3mb)
Tryon Creek Restoration Monitoring Project 2005-2007 Progress Report
Tryon Creek Habitat Restoration Monitoring powerpoint (1.2 mb)

For more information, contact Mike Hudson at 360-604-2575 or email

Last updated: December 7, 2012
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