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Spokane, WA 99202
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Phosphorus Bioavailability Study

Researchers at the University of Washington are currently conducting a study to determine the bioavailability of phosphorus sources in the Spokane River watershed.  The study is outlined in the quality assurance project plan.

Study Quality Assurance Project Plan 

The study is funded by the Washington State Department of Ecology in partnership with Spokane County, the cities of Coeur d'Alene, Post Falls, and Spokane, the Hayden Area Regional Sewer Board, the Liberty Lake Sewer and Water District,  Inland Empire Paper Company, Kaiser Aluminum, and the Water Environment Research Foundation.

Sample collection for the study began in August 2009 and is planned to be completed in June 2010.  The phosphorus sources include samples from:

  • The Spokane River at Nine Mile
  • City of Spokane Riverside Park Water Reclamation Facility
    • Effluent from secondary treatment
    • Effluent from pilot tertiary treatment processes
  • Inland Empire Paper pilot tertiary treatment process
  • City of Coeur d'Alene wastewater tertiary treatment pilot processes
  • Hayden Area Regional Sewer Board secondary treatment effluent
  • Liberty Lake Sewer and Water District secondary treatment effluent
  • City of Post Falls secondary treatment effluent


Results from the first several sampling rounds were presented on January 27, 2010. The presentation slides are available:  Presentation 7 MB

The principal investigator for the study is:
Michael T. Brett
Department of Civil & Environmental Engineering
University of Washington