Water Quality Improvement Project
Palouse River Mainstem

Introduction

The Palouse River enters Washington State near the town of Palouse and flows west through a variety of terrain until it meets the Snake River downstream of Hooper and the Palouse Falls. When you take into account the drainage areas of all of the Palouse River tributaries, this is one of the largest watersheds in Washington. Therefore, much of Ecology’s initial water quality work has focused on the main stem Palouse River and tributaries known to be impaired. The studies described on this page are limited to the Palouse River, Rebel Flat Creek, and the mouths of several other tributaries.

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.

Water quality issues

The Palouse River is listed as impaired for dissolved oxygen, pH, fecal coliform bacteria, temperature, and several historical pesticides and PCBs. To learn more about the importance of these various parameters, please see our water quality impairments page.

Status of the projects

Due to the size of the watershed and multiple water quality impairments along the Palouse River, water quality improvement efforts are separated into several individual projects. While the studies and reports for each of these projects may be separate, implementation activities to address one water quality problem also typically help the other issues. Project summaries with links to more specific information follow.

North Fork Palouse River Dissolved Oxygen and pH

The most recent study of the Palouse River examined dissolved oxygen and pH, which are influenced by excess nutrients. The current efforts on dissolved oxygen and pH only address the North Fork Palouse River (from the state line to the river's confluence with the South Fork Palouse River in Colfax). Data for this study was collected in conjunction with the bacteria study, and intensive surveys were conducted in Summer 2007 and 2012. Data on the North Fork Palouse River indicates that at times it has too little oxygen and the pH is too high to support healthy fish and other aquatic life. The concentrations of nitrogen and phosphorus in the river affect the amount of plant and algae growth in the water. Plants affect both oxygen and pH levels in water bodies through photosynthesis and respiration.

A water quality improvement report describes the dissolved oxygen and pH problems in the North Fork Palouse River and what needs to be done to bring the river back into compliance with water quality standards. This report was reviewed and approved by the Environmental Protection Agency (EPA) in December 2016. For more information see the Palouse River Area: Dissolved Oxygen and pH webpage.

Dissolved oxygen and pH impairments on the lower Palouse River, downstream of the confluence with the South Fork Palouse River, are outside the scope of this project and be addressed in the future.

Palouse River Temperature

Another study, also initiated in 2007, examined contributions to high water temperature. Water temperature affects the health and distribution of fish and other aquatic life. This study ran from May - October 2007, during the time of year when the water was most likely to be impaired. A report on the study findings and an implementation plan to address the issues contributing to human causes of high water temperature was completed and submitted to the Environmental Protection Agency for their review and approval on July 17, 2013. EPA approved the report on November 5, 2013.

Palouse River Fecal Coliform Bacteria

(Excluding the North Fork Palouse River – see see North Fork Palouse River Fecal Coliform Bacteria)

A study, initiated in 2007, examined the levels and distribution of fecal coliform bacteria throughout the watershed. Fecal coliform bacteria come from the intestinal tracts of humans and warm-blooded animals. It can indicate the presence of human and animal waste which may carry disease-causing organisms. The Palouse River and Rebel Flat Creek are impaired by fecal coliform bacteria. This study ran from May 2007-May 2008 and a report and implementation plan outlining actions to reduce bacteria were published in December 2010. EPA reviewed the report and approved it March 2011.

Note: The portion of the Palouse River from the Idaho border to Colfax (also known as the North Fork Palouse River) was addressed under the North Fork Palouse River Bacteria TMDL.

Palouse River Toxics (including the South Fork Palouse River)

Previous studies found high levels of historical pesticides and PCBs in Palouse River fish. So, in May 2005 Ecology began the first study to examine several toxins in the Palouse River. A TMDL report detailing how the Palouse River will achieve water quality standards for PCBs and dieldrin (the only chlorinated pesticides still above standards) was completed and submitted to the Environmental Protection Agency (EPA). EPA approved the TMDL on November 9, 2007.

North Fork Palouse River Fecal Coliform Bacteria

The first project initiated in the Palouse Watershed was the development of a plan to address fecal coliform bacteria in the North Fork Palouse River. This effort was lead by the Palouse Conservation District (PCD). The PCD provided their monitoring data and implementation plan to the Department of Ecology to develop into a TMDL to comply with the Clean Water Act.

Other water bodies in this watershed

Cow Creek is also listed as impaired for dissolved oxygen, fecal coliform bacteria, and temperature. An evaluation of the on-going implementation activities on Cow Creek determined that these activities should address these water quality problems. Therefore, these impairment listings have been reclassified as category 4b (addressed by a pollution control plan) on Washington's Water Quality Assessment.

Pleasant Valley Creek is listed as impaired for fecal coliform bacteria and pH. This stream is outside the scope of this project and will be addressed at a later date.

 

Technical information

 

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Last updated January 2017
 

PROJECT INFO

Location:
WRIA: #34 (Palouse)
County: Whitman

Water-body Names:
Palouse River
Cow Creek
Rebel Flat Creek
Rock Creek

Parameters:
Dissolved oxygen
Fecal coliform bacteria
Nutrients
pH
Temperature
Toxins

# of TMDLs:
DO and pH - 28
Fecal Coliform - 3
Temperature - 2
Toxins - 4

Status:
Toxins - TMDL approved by EPA, has implementation plan.
Fecal coliform - TMDL approved by EPA, has implementation plan.
Temperature - TMDL approved by EPA, has implementation plan.
Dissolved Oxygen and pH - TMDL approved by EPA, has implementation plan.

Contact Info:
Elaine Snouwaert
Phone: 509-329-3503
Email: Elaine.Snouwaert@ecy.wa.gov

Eastern Region
Department of Ecology
4601 N Monroe Street
Spokane, WA 99205-1295