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Upper Yaquina Watershed Project

TMDL Title: Upper Yaquina Watershed TMDL and WQMP
Water Quality Limited Parameters: Bacteria (water contact recreation), dissolved oxygen (aquatic life protection)
Pollutants: E. coli, total phosphorus, solar radiation
Status: In process of completing a new TMDL and WQMP

Project summary

DEQ is preparing Total Maximum Daily Loads and a Water Quality Management Plan to address water quality impairments for dissolved oxygen and bacteria within the Upper Yaquina River watershed along the Oregon Coast. These impairments affect two primary beneficial uses – aquatic life and recreation that involves contacting water, such as fishing and swimming. The watershed occupies about 54,000 acres and is located mostly within Benton and Lincoln counties, with a small portion in Polk County (see map). Land ownership and management is predominately industrial and public forest with a smaller percentage of agriculture and rural residential. There are no incorporated cities, and named places include Eddyville, Nashville and Summit.

The primary pollutants in the watershed are E.coli, total phosphorus, and excess solar radiation. The scale of the analysis varies depending on the parameters:

  • Bacteria (E. coli): The bacteria TMDL will apply to both the mainstem and contributing watershed tributaries. The technical analyses indicates that microbiological water quality standards can be met through reduced inputs of domestic livestock manure, including improved riparian zone conditions that provide adequate filtration of pasture runoff. Failing septic systems also need to be promptly repaired or replaced in order to maintain safe conditions for water contact recreational use.

  • Dissolved oxygen: The dissolved oxygen TMDL will address both the designated spawning and non-spawning periods for the mainstem Upper Yaquina River. The technical analyses are primarily based on two models that link watershed processes with instream water quality conditions. The analysis identified excess phosphorus and solar radiation loading as the primary pollutants that must be reduced from major land use sectors to achieve water quality standards for dissolved oxygen. This analysis indicates that spawning criterion will be met once pollutant load reductions are met, thereby providing a pathway for identifying both the mainstem Upper Yaquina River and Little Elk Creek as “attaining" and, ultimately, removing these from the list of impaired waterbodies.
DEQ convened a rulemaking advisory committee to inform the TMDLs rule proposal. The Environmental Quality Commission adopted the TMDLs and Water Quality Management Plan rules at their Sep. 15, 2023 meeting. Information on the rulemaking process is available on the rulemaking website.


In March 2012, DEQ convened a Local Stakeholder Advisory Committee (LSAC) to provide input on the development of Mid-Coast Basin TMDLs and to assist with implementation planning. The LSAC and technical working groups met periodically from March 2012 to April 14, 2022. This process involves many active stakeholders and partners in the Basin, including several local, state and federal agencies.

Since late 2017, the Mid-Coast Basin TMDLs development activities have been focused primarily on dissolved oxygen conditions assessment, data analysis and model development. Activities for bacteria, temperature and sediment impairments were temporarily or indefinitely suspended pending resolution of matters directly related to the temperature TMDLs litigation and the Willamette Basin mercury TMDLs litigation. For more information, contact Gene Foster, Watershed Management Section at 503-229-5325.

Updated status information and TMDL development schedules are periodically provided to the Committee at meetings and through written updates posted here. TMDL development activities are primarily focused on the Upper Yaquina watershed.

Most recent LSAC meeting information:

Meeting 11, April 14, 2022

Group and topics:
Upper Yaquina watershed - preliminary TMDL analysis outputs and load allocations for Bacteria and Dissolved Oxygen impairments​; Discussion (DEQ and LSAC)

Supporting documents:

Other TMDLs in the Mid-Coast Basin



David Waltz
Coquille Basin Coordinator

Steve Mrazik
Program Manager

Basin Coordinator List (Modified: 5/10/21)

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