Water Quality Index

The Oregon Water Quality Index analyzes a defined set of water quality variables and produces a score describing general water quality for a particular monitoring site in the ambient monitoring network. Scores correspond to a water quality status and are evaluated for improving or declining trends at each site. The status and trend analyses incorporate 10 years (currently water years 2013-2022) of water quality data.

• View the Water Quality Index Map

Oregon water quality reports and documents

• 2025 Oregon Water Quality Index
  
• 2024 Data Summary
  
• 2023 Data Summary
  
• 2022 Data Summary
  
• 2021 Data Summary
  

Reference materials

• Story Map: What's in the Water Quality Index?
  
• WQI: Background, Analysis, and Usage  
  

Data downloads

Summary Basin Tables

Oregon Water Quality Index Summary Basin Tables are now available in one file with separate tabs.

• Oregon Water Quality Index Summary Basin Tables
  

Raw Data and Historical Status and Trends