Federal, state and tribal agencies release workplan and schedule to assess dissolved oxygen in Spokane River and Lake Spokane.

On September 26, 2008 EPA issued a policy statment saying “Therefore, under the current standards, both the TMDL and the Idaho NPDES permits need to be revised so that, taken together, all sources in Washington and Idaho are accounted for and appropriate limits set that do not exceed the .20 mg/l decrease in dissolved oxygen allowed under the Washington dissolved oxygen standard.” This policy has significant implications for the future operations of waste water treatment plants releasing effluent into the Spokane River. See attached file below for full statement.

To address EPA’s policy standard, Washington DOE, Idaho DEQ and the Spokane Tribe are working together on a water quality model that will evaluate the impacts of phosphorus on dissolved oxygen in the Spokane River and Lake Spokane. The results of the water quality model will be used to develop both the Washington TMDL, and the Washington and Idaho NPDES permits.

The work plan describes the objectives, structure, responsibilities, personnel, and decision-making process that will be used by the four agencies to develop the inter-state Spokane River water quality model. A letter describing Ecology’s interpretation of the Washington water quality standard for dissolved oxygen in Lake Spokane is provided as a separate attachment. A schedule for completing the modeling and associated dissolved oxygen TMDL and wastewater permits is also provided as a separate attachment.

The schedule attached to this post was updated on January 20, 2009.