TMDL Background

Waters of the State of Oregon are monitored by the Oregon Department of Environmental Quality (ODEQ) and other agencies. This information is used to determine whether water quality standards are met, and consequently, whether beneficial uses of waters are fully supported. Section 303(d) of the federal Clean Water Act (CWA) calls for a list of water quality limited waters and requires the establishment of a total maximum daily load (TMDL) for each pollutant of concern. ODEQ is responsible for assessing data, compiling the 303(d) list and developing TMDLs. Both the list and TMDLs are submitted to the US Environmental Protection Agency (EPA) for approval. TMDLs are assessments that determine the maximum amount of pollutant that can be present in a waterbody while meeting water quality standards.

This loading capacity can be allocated to point, nonpoint and future sources of pollution. Uncertainty and natural pollutant sources are accounted for as well. Point sources are those associated with discrete human-made conveyances such as pipes from waste water treatment plants. Wasteload allocations are the portion of the TMDL attributed to point sources. Nonpoint sources are diffuse sources such as field runoff or excess solar radiation due to vegetation removal. Load allocations are the portion of the TMDL attributed to either natural background or nonpoint sources. TMDLs are implemented via water quality management plans and, in the case of point sources, permits issued through the National Pollutant Discharge Elimination System (NPDES).

The Walla Walla TMDL plan (for stream temperature on the Oregon side of the basin) has been through the public comment and review process and the final revised version was approved by the US EPA on September 29, 2005. This is the culmination of 4+ years of data collection, analysis and public outreach for WWBWC and ODEQ.  A grant for water quality data collection from the Oregon Watershed Enhancement Board (OWEB) has supported this work, as well as several grants from EPA-319 funds.

The assessment document (technical appendix) outlines and analyzes the science behind the TMDL temperature load allocations being determined for the Walla Walla River.  The TMDL plan itself reflects the policy outcome of the TMDL.  While the assessment (technical appendix) document is a fairly technical read, the policy and management plan document is written for a more general audience.  You can view or download the TMDL and WQMP documents, and comment response and fact sheets Click Here.

Copies on CDs are also available from Don Butcher at ODEQ (541) 278-4603, or from Bob Bower at WWBWC, (541) 938-2170.

WWBWC received the following comments in a letter announcing the EPA approval of the TMDL plan:
"The Department of Environmental Quality appreciates the outstanding efforts of the Walla Walla Basin Watershed Council in data collection and management, community outreach, analysis and guidance throughout the stream temperature assessment and preparation of this document. We are grateful as well for the contributions of the organizations listed below. DEQ believes that the participation and mutuality that characterized the TMDL development process in the Walla Walla Subbasin will facilitate progress and interaction in the years to come."

Prior comments from Don Butcher, ODEQ, OR TMDL contact for the Walla Walla Subbasin:
"Many organizations and people have greatly supported this effort, with technical assistance, data and funding. This relatively informal partnership has included: The Walla Walla Basin Watershed Council, Washington Dept. of Ecology, Confederated Tribes of the Umatilla Indian Reservation, US Army Corps of Engineers, Washington Dept. Fish and Wildlife, Oregon Dept. Fish and Wildlife, Umatilla National Forest, US Environmental Protection Agency, and others. In particular, the Watershed Council has worked side by side with DEQ throughout the process, co-developing the model, and has provided an abundance of high quality data, insight, basin knowledge and outreach.

The TMDL allocations and planning we did apply only in Oregon. The Washington Department of Ecology (WDOE) is currently developing TMDLs for the Washington part of the Subbasin.  We at ODEQ appreciate the collaborative watershed process that we see in the Walla Walla Basin and look forward to ongoing teamwork.

ODEQ has now carried out the next step of the TMDL process - notification to designated management agencies of their responsibility to fill in the WQMP placeholders with sector specific implementation plans.  This will include development of detailed management plans based on the allocations in the TMDL and as described in the WQMP.  We will continue to work closely with TMDL-designated management agencies and other watershed groups."

-Don Butcher, Oregon DEQ, Pendleton Office (541) 278-4603
 

For other information about the TMDL development process, please see:

• Oregon DEQ's TMDL Documents

• Washington DOE's TMDL page

• WDOE's Walla Walla Watershed TMDLs page

• WDOE's page on Quality Assurance Project Plan for Walla Walla River Tributaries Temperature TMDL

• EPA's Pacific Northwest Temperature Criteria Guidance Project

  (to develop water quality criteria for the protection of Northwest native salmon)