freshwater monitoring

Freshwater Monitoring

River and Stream Water Quality Index

How is your river doing?

Bill Ward sets thermistor

Even if you know that your local river or stream has a pH of 7.1 and that oxygen levels are at 12 milligrams per liter, you may not know what that means for the health of your stream or of its plants and animals. However, the Water Quality Index for your stream can help you learn much about its relative health.

The Water Quality Index

The Water Quality Index, or WQI, summarizes and presents water-quality data in an easily understood format. It is a number ranging from 1 to 100; a higher number indicates better water quality. In general, stations scoring 80 and above met expectations for water quality and are of "lowest concern," scores 40 to 80 indicate "moderate concern," and water quality at stations with scores below 40 did not meet expectations and are of "highest concern." The WQI graphs show beige for low concern, blue for moderate concern, and reddish pink for high concern or poor water quality.

 KEY   blue - good    beige - moderate    red - poor 

Finding the Water Quality Index

The Water Quality Index is in a tab on individual station pages in the Statewide Water Quality Monitoring Network application. Select your station of interest from the application map, and click the blue link to get to the station page. The tabs are towards the bottom of the page. Under the Water Quality Index tab, below some further instructions and explanation, are the index graphs. The amount of time covered varies by station. However, each has four graphs: scores for the most recent water year, scores by constituent, scores by month, and general WQI trends for that station year by year. The "scores by constituent" include eight analytes, including fecal coliform bacteria, dissolved oxygen, and temperature. 

The development of the WQI

A Water Quality Index for Ecology's Stream Monitoring Program  is a report that describes the development of and the methodology for the Water Quality Index.

Calculate WQI based on your own data

The Water Quality Index spreadsheet (Version 6) is a downloadable tool for calculating a WQI score based on your own data.

Other statewide indicators

Ecology's water-quality data informs other statewide indicators of water quality.

Cool, Clean Water is a freshwater indicator for the Governor's Results Washington quality summary.

Freshwater Quality is a dashboard indicator for the Puget Sound Partnership.