Water Quality Improvement Project
As part of a larger effort to address all water quality impairments
in the Palouse River watershed, in 2007 Ecology began a project to
address high temperatures in Palouse River. This project addresses the
Palouse River from the state line with Idaho to the mouth. The mouths of
major tributaries are also included.
The South Fork Palouse River is a major tributary with multiple water quality
problems. Please see the South Fork Palouse River
Project page for more information on studies in this sub-watershed.
Why this matters
Elevated water temperature is a common problem throughout Washington.
High temperatures contribute to stream habitats unable to support
healthy populations of fish and other aquatic animals. Warm water
affects fish’s metabolism, susceptibility to toxins and disease,
reproduction, and their food supply. It can also hold less dissolved
oxygen than cold water, so it makes it difficult for fish and insects
that breathe through the water.
Status of the projects
The temperature study ran from May 2007-October 2007, during the time
of year when the water is most likely to be impaired. Water quality
modeling indicates that even under historical natural conditions the
water temperature would not be likely to meet the numeric criteria
during July and August. Therefore, the goal of this TMDL will be to
return this river’s temperature regime to natural conditions, which will
be accomplished by reestablishing “system potential shade” along the
river’s stream banks. System potential vegetation consists of the plants
that would naturally grow at the site as determined by climate,
elevation, soil properties, and other factors.
Ecology worked with several organizations in the watershed to draft an
implementation plan describing methods to address issues contributing to
elevated temperatures. These issues include degraded riparian areas and
wetlands, changes to natural stream hydrology, erosion, and wastewater
This plan was available for public review and comment from May 16 through
June 14, 2013. Comments were reviewed and responded to in an appendix to the
final version of the report was revised in response to the comments and was
submitted to the Environmental Protection Agency for their review and approval
on July 17, 2013. EPA approved the report on November 5, 2013.
Unless otherwise specified the following documents are Ecology publications.
Palouse Temperature Total Maximum Daily Load: Water Quality Improvement Report
and Implementation Plan
Quality Assurance Project Plan: Palouse River
Temperature Total Maximum Daily Load Study
Streamflow Summary for the Palouse and South Fork Palouse Rivers and Selected
WRIA 34: Palouse Watershed Information (Environmental Assessment Program web
Back to top of page
WRIA: #34 (Palouse)
Rebel Flat Creek
# of TMDLs:
Temperature - 2
Temperature - TMDL approved by EPA, has implementation plan.
Department of Ecology
4601 N Monroe Street
Spokane, WA 99205-1295