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Oregon / Washington

Trask River

The Trask River watershed is approximately 175 square miles (112,164 acres) in size and is located primarily within Tillamook County, with small portions in Washington and Yamhill counties. The Trask River is one of five major rivers in the Tillamook basin (which also includes the Tillamook, Wilson, Kilchis, and Miami rivers) that originate in the northern Oregon Coast Range and drain into Tillamook Bay. For the purposes of this analysis, the Trask watershed is subdivided into eight subwatersheds (6th field watersheds), which will be the basic units for many analyses in this report. Seven of the eight subwatersheds are located in the forested uplands of the Oregon Coast Range; the eighth subwatershed is located in the floodplains of the lower Trask River. Barney Reservoir in the Middle Fork of the North Fork subwatershed is the primary municipal water supply for the cities of Beaverton, Hillsboro, and Forest Grove.

Click on titles to navigate to specific documents. For ease of function, the Trask River Watershed Analysis and the maps are separate Adobe Acrobat PDF files.

Trask River Watershed Analysis Part 1 (PDF)
Trask River Watershed Analysis Part 2 (PDF)

Map Title Number
Location (PDF) Fig 1.1
Elevation (PDF) Plate 1
Slope Steepness (PDF) Plate 2
Vegetation Dams (PDF) Plate 3
Land Use (PDF) Plate 4
Streambank Erosion (PDF) Plate 5
Coho Chum Runs (PDF) Plate 6
Spring/Fall Chinook Runs (PDF) Plate 7
Summer/Winter Steelhead Runs (PDF) Plate 8
Habitat Surveyed (PDF) Plate 9
Road Crossings (PDF) Plate 10
Riparian Vegetation (PDF) Plate 11
Road Segments (PDF) Plate 12
Water Temperatures (PDF) Plate 13