Total Maximum Daily Loads

This site contains links to Total Maximum Daily Load and Water Quality Management Plan documents prepared for waterbodies in Oregon designated as water quality limited on the 303(d) list. A TMDL is the calculated pollutant amount that a waterbody can receive and still meet Oregon water quality standards.

General information

The TMDL process determines how much of a pollutant a water body can receive without violating the water quality standard. The DEQ Laboratory staff is involved in the process by developing sampling plans to characterize baseline water quality conditions. The Laboratory also gathers data once the TMDL plan has been implemented to help determine if water quality has improved. Objectives of the Program:

Objectives of the Program

  • Intensive Watershed Assessments
  • Characterize sources and loads
  • Develop Conceptual and Mathematical Models
  • Establish Assimilative Capacity, Limiting Factors, Waste Load Allocations

Extent of Monitoring

Depending on the TMDL data needs, some or all of the following data may be collected:

  • Hydrology: Flow, Time of Travel, Seasonal Variability, Groundwater Affects
  • Chemistry: Longitudinal Sampling Surveys, Synoptic Sampling Surveys, Source Studies
  • Temperature: Shading and Channel Characteristics, Temperature
  • Biological: Fish, Macro-invertebrates, Algae Sampling
    May span several years with hundreds to thousands of samples

2007 study basins: Yamhill, Pudding, Coos, Tillamook, Johnson Creek(Portland), Alsea/Siuslaw, Coquille, Willow Creek(Heppner), Powder

2008 study basins: Yamhill, Tillamook, Yaquina, Alsea, Siuslaw, Salmon, Beaver Creek (Mid-coast), Coquille, Floras Crk, Hunter Crk, Pistol, Calapooya Creek, John Day, Middle Deschutes

How data are used



DEQ/EPA Memorandum of Agreement

DEQ and EPA signed an MOA on Feb. 1, 2000. The purpose of the MOA is to formalize the commitment to complete TMDLs in Oregon on a 10 year schedule. In addition, the MOA describes the components of a TMDL and that an implementation strategy and plans will be included with TMDLs that DEQ develops.

Consent decree

A Consent Decree between the US Environmental Protection Agency and Northwest Environmental Defense Center, John R. Churchill, and Northwest Environmental Advocates was approved and signed on Oct. 17, 2000 regarding the establishment of TMDLs based upon the Feb. 1, 2000 MOA between EPA and DEQ. The Consent Decree lists the cumulative number of TMDLs to be established through 2010.


Basin Coordinator List

Gene Foster , Watershed Management Manager, 503-229-5325