Learn more about how the District plans to address this resource concern in the Long-Range Business Plan for 2011-2015 (pdf file).
The Tualatin River and tributaries are used for fish and wildlife, irrigation, drinking water, supporting industries, and recreational purposes such as swimming, fishing, and boating. All of these beneficial uses are affected by the water quality in the Tualatin River Watershed.
What is a watershed?
A watershed is an area of land that drains into a lake or river. We all live in watersheds. What we do in the watershed impacts the water running into the lake or river.
Tualatin River Watershed
Tualatin River Watershed
The 84-mile long Tualatin River drains over 900 miles of streams and a land area of 712 square miles. The Tualatin River Watershed contains all of Washington County and portions of Clackamas, Columbia, Multnomah, Tillamook and Yamhill counties. Located in the northwest corner of the Willamette River Basin, the watershed is bordered by the Coast Range Mountains to the west, the Tualatin Mountains to the north and east, and the Chehalem-Parrett Mountains to the south. The Tualatin Watershed has six main sub-watersheds: Dairy-McKay, Gales, Upper Tualatin-Scoggins, Middle Tualatin, Rock, and Lower Tualatin.
There are watershed analyses for each of the sub-watersheds:
- Upper Tualatin-Scoggins Watershed Analysis, 2000
- Gales Creek Watershed Assessment Project, 1998
- Dairy-McKay Watershed Analysis, 1999
- Middle Tualatin-Rock Creek Watershed Analysis, 2001
- Lower Tualatin Watershed Analysis, 2001
The watershed is home to several important salmon species.
Resident salmonids in the Tualatin Watershed include cutthroat trout (Oncorhynchus clarki) and rainbow trout (O. mykiss). Anadromous salmonids in the Tualatin Watershed include fall Chinook salmon (O. tshawytscha), coho salmon (O. kisutch) and winter steelhead (O.mykiss).
There are many factors that limit salmon in the watershed.
Both point source (specific location) and nonpoint source (run off from crop, forest, urban landscapes) pollution affect water quality. Salmon are limited by low summer flows, high summer water temperatures, limited spawning and rearing areas, high turbidity, low hydraulic diversity, and predation by non-native species.
Water Quality Regulations
In response to the Federal Clean Water Act (CWA) of 1972, the Oregon Department of Environmental Quality (DEQ) listed the Tualatin River and its tributaries as “water quality limited.” Once a river has been designated as water quality limited, the CWA requires that Total Maximum Daily Loads (TMDLs) be developed for that water body. DEQ’s 303(d) list shows water quality limited waterbodies in Oregon.
What is the Agricultural Water Quality Management Act?
Oregon’s Agricultural Water Quality Management Act (Senate Bill 1010) was created in 1993 with the input and support of the agricultural industry and the State Board of Agriculture to further help the industry address agricultural water quality issues. Working in partnership with the 45 local Soil and Water Conservation Districts, the Oregon Department of Agriculture identified 39 watershed-based Agricultural Water Quality Management Areas across the state.
Working with the ODA and a Local Advisory Committee (LAC) made up of local farmers and community members, the Tualatin SWCD created the Tualatin River Subbasin Agricultural Water Quality Management Area Plan. This Plan provides guidance for addressing agricultural water quality issues in the Tualatin River Watershed.
