Water Quality Monitoring

person sampling water from a creekWe invite you to view the 2018 Water Quality Monitoring Report.

In addition, results of summer 2018 monitoring in McCarthy Creek have been mailed to landowners in the area. This study aimed to identify elevated TSS concentrations and yields during storm events on both mainstem and tributary sampling locations, establish the relationship between Total Suspended Solids (TSS) and rainfall variables (rainfall depth, rainfall intensity, and rainfall duration), and determine the most significant land cover variables as predictors of TSS based on delineated sub-watersheds in McCarthy Creek. Read a summary of the results here.

Since 2009 West Multnomah SWCD has been monitoring streams in the rural Tualatin Mountains (“West Hills”). The Water Quality Monitoring Program is intended to guide the strategic planning of WMSWCD while continuing to inform our restoration work and the story of how these watersheds are faring through time. The selection of the focus or “study area” has been driven by a lack of existing data (prior to 2009), finding salmon in McCarthy Creek, and the emphasis of these watersheds in the WMSWCD strategic plan.

Water quality data for perennial streams flowing out of the Tualatin Mountains is quite limited. Streams located within the City of Portland are often monitored by the Bureau of Environmental Services while streams on the south side of the Tualatin Mountains, which eventually flow into the Tualatin River, are monitored by Clean Water Services. However, the quality of streams in the rural areas of the Tualatin Mountains, which flow north into the Multnomah Channel, is poorly understood.

While none of the creeks in the study area have been identified through the Oregon Department of Environmental Quality’s “303d” program, mainly due the relatively small size of the watersheds, questions have remained about the status of these creeks. Inadequate riparian areas and upland land uses (forestry and agriculture) are expected to impact water quality, however the magnitude is unknown.

The Water Quality Program focuses on the watersheds of Miller, McCarthy and Crabapple/Patterson Creeks. These are the largest watersheds within the study area and flow year-round. As a result they have the potential to be “salmon bearing” have been labeled as “priority watersheds” through the Conservation District’s strategic planning process. We have seen salmon in Miller and McCarthy Creeks and McCarthy is listed by the Oregon Department of Fish and Wildlife as Essential Salmonid Habitat or ESH.

For more details on the water quality program, click here.

For more information on the watersheds in our District, please see the Watersheds page.  Results from the Water Quality Program, along with our salmon sightings in 2012, make McCarthy Creek a focus watershed of the Healthy Streams Program, which provides free riparian habitat restoration.


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