Spokane River DO TMDL home > Background

Background

Ecology began working on a Dissolved Oxygen Water Quality Improvement Project (TMDL) in 1998. In the fall of 2000, Ecology contracted with the U.S. Army Corps of Engineers (USACE) to apply the CE-QUAL-W2 model to the Spokane River and Lake Spokane system. The USACE collaborated with Portland State University. A report (Cusimano, 2004) on the water quality study and modeling effort was completed in 2004 (see Technical Information page for a link to the report).

In October 2004, Ecology released a draft TMDL for public comment. Prior to the release, entities that discharge to the Spokane River (the Dischargers) developed a Use Attainability Analysis and submitted a petition for rule making to revise the dissolved oxygen water quality criteria for the Spokane River and Lake Spokane. Shortly thereafter, Ecology and the Dischargers agreed to withdraw the petition, put the draft TMDL on hold and develop an implementation plan for the TMDL. This led to the creation of the Spokane River TMDL Collaboration (Collaboration).

The Collaboration included Ecology, the Dischargers, local governments, Idaho Department of Environmental Quality (IDEQ), the U.S. Environmental Protection Agency (EPA), the Spokane Tribe of Indians, environmental groups, and power companies. The Collaboration developed the Foundational Concepts for the Spokane River TMDL Managed Implementation Plan. The Collaboration agreed that the TMDL’s Managed Implementation Plan will be consistent with the principles described in the Foundational Concepts. The agreement was formalized through a Memorandum of Agreement signed on March 7, 2007.

During 2007, Ecology worked with Portland State University to run some additional model scenarios to incorporate modifications to the modeling approach as a result of the Collaboration. The dissolved oxygen TMDL has been revised to reflect the Foundational Concepts and the new modeling.  The draft report, Spokane River and Lake Spokane Dissolved Oxygen Total Maximum Daily Load, Water Quality Improvement Report was distributed for a 45-day public comment period in September 2007.

Ecology appreciates the effort made by all the individuals and organizations that provided comments to address the critical issues in the previous draft plan.