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Water Quality Status and Trends Analysis

DEQ produces a statewide water quality status and trends report each year. The analysis is intended to answer these four questions:

  • What is the status of water quality in Oregon? Are waterbodies attaining water quality standards for bacteria, dissolved oxygen, pH, and temperature?
  • Where applicable, are Total Maximum Daily Load (TMDL) targets established for total phosphorus or total suspended solids being attained?
  • What are the trends in water quality?
  • What watershed restoration or protection actions have been implemented?

DEQ conducts this analysis by assembling surface water quality data and information about watershed restoration or protection actions implemented from readily accessible public databases, comparing these water quality data to the appropriate Oregon water quality standards or TMDL targets, and determining the status and trends where data and information of sufficient quality and quantity are available. Results are summarized for each of the 19 administrative basins in Oregon as well as the Columbia and Snake Rivers.
The results of this analysis informs DEQ, other state and federal agencies, and the public on the condition of waters and if TMDL targets are being achieved; if water quality is improving or degrading; the pace of improvement or degradation; what actions, if any, are being taken to improve water quality, and where water quality data are and are not being collected.