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Scientific Investigations Report 2012–5068

Reconnaissance of Contaminants in Selected Wastewater-Treatment-Plant Effluent and Stormwater Runoff Entering the Columbia River, Columbia River Basin, Washington and Oregon, 2008–10

Table 2. Descriptions of wastewater-treatment plants where samples were collected, Columbia River Basin, Washington and Oregon, 2008–09.

[Cities shown in downstream order. Abbreviations: Mgal/d, million gallons per day; 7Q10, the lowest streamflow for 7 consecutive days that occurs on average once every 10 years; ft3/s, cubic foot per second; UV, ultraviolet; WWTP, wastewater treatment plant; NA, not available]

City Station name Point of 
River mile

Permit design flow

Columbia River 7Q10 streamflow

plant description
Wenatchee City of Wenatchee WWTP effluent at Wenatchee, Wash. 466.6 7.1 51,557 Activated sludge plant, secondary-level treatment and UV disinfection.
Richland City of Richland WWTP effluent at Richland, Wash. 337.1 11.4 52,700 Semi-plug flow conventional activated sludge, secondary clarification, and chlorination.
Umatilla City of Umatilla WWTP effluent at Umatilla, Oreg. 289 0.92 NA Oxidation ditch with UV disinfection.
The Dalles City of The Dalles WWTP effluent at The Dalles, Oreg. 189.5 4.15 80,637 Activated sludge plant with UV disinfection.
Hood River City of Hood River WWTP effluent at Hood River, Oreg. 165 2 74,000 Activated sludge plant with UV disinfection.
Portland Columbia Blvd WWTP effluent at Hayden Island, Oreg. 105.5 72 79,436 Conventional activated sludge, secondary clarification, chlorine disinfection.
Vancouver Vancouver Westside WWTP effluent at Vancouver, Wash. 105 28 79,436 Industrial Pretreatment Lagoon, secondary activated sludge, UV disinfection, sludge incineration.
St. Helens City of St. Helens WWTP effluent at St. Helens, Oreg. 86.9 45 88,900 Combined municipal and kraft mill aerated stabilization basin.
Longview Three Rivers Regional WWTP effluent at Longview, Wash. 67.5 26 97,400 Conventional activated sludge, secondary clarification, chlorine disinfection, dechlorination.

First posted April 25, 2012

For additional information contact:
Director, Oregon Water Science Center
U.S. Geological Survey
2130 SW 5th Avenue
Portland, Oregon 97201

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