TMDL title: Temperature TMDLs for the Umpqua River Basin (North Umpqua, South Umpqua, and Umpqua Subbasins)
Water Quality Limited Parameters: Temperature
Schedule: DEQ will present the Umpqua River Basin TMDL to the Environmental Quality Commission for proposed rule adoption in November 2024 to give EPA a minimum of 30 days for their approval or disapproval by Feb. 28, 2025.
Project Area: This TMDL project includes the applicable area within the North Umpqua Subbasin, the South Umpqua Subbasin and the Umpqua Subbasin.
The project schedule for all replacement temperature TMDLs is online. To stay informed of this possible schedule change and other project related information, please sign up for email updates on our main TMDL Replacement Project page.
In 2013, the United States Environmental Protection Agency disapproved the Natural Conditions Criterion contained in Oregon's water quality standard for temperature due to the 2012 U.S. District Court decision for NWEA v. EPA, 855 F. Supp. 2d 1199 (D. Or., 2012). This portion of the temperature water quality standard was used in most temperature TMDLs issued from 2003 through 2012. On Oct. 4, 2019, the U.S. District Court issued a judgment for NWEA v. EPA, No. 3:12-cv-01751-HZ (D. Or., Oct. 4, 2019) and required DEQ and USEPA to replace 15 Oregon temperature TMDLs that were based on the Natural Conditions Criterion and to reissue the temperature TMDLs based on the remaining elements of the temperature water quality standard.
A Total Maximum Daily Load is a water quality restoration plan and the calculation of the maximum amount of a pollutant that a waterbody can receive while still meeting water quality standards for that particular pollutant. The maximum amount of loading a waterbody can receive is called the loading capacity. Loading from all pollutant sources must not exceed the loading capacity of a waterbody, including an appropriate margin of safety.
Quality Assurance Project Plans: Umpqua River Basin
A Quality Assurance Project Plan is developed prior to writing the TMDL and does the following:
- Defines the issue and objectives of the TMDL, including the spatial and temporal extents of the water quality impairments
- Provides a high-level description of the key processes and variables for temperature
- Outlines the overarching technical approach for the TMDL, including the appropriate modeling and analytical tools to be used
- Provides the data sources for defining and creating inputs to the models, including data that were used in the modeling for the original TMDLs, if an original exists
Examples of these inputs can include meteorological data, stream flow and temperature, point sources and vegetation characteristics.
- Describes how the analysis and modeling will be evaluated for acceptability
- Describes potential scenarios for evaluating management strategies for reducing anthropogenic thermal loads
- Provides various aspects for managing the TMDL development project, including documentation, the project team, data, and records management
View the Umpqua River Basin Interactive Map