Water Quality Index for Streams and Rivers

View WQI scores for another water year. View annual WQI score report for all streams

Map Legend
	Low concern
	Moderate concern
	High concern

Click on the station dot for a link to the most recent WQI score report.

The WQI is a unit-less number ranging from 10 to 100: the higher the number, the higher the water quality. For temperature, pH, fecal coliform bacteria, turbidity, and dissolved oxygen, the index expresses results relative to levels required to maintain beneficial uses according to criteria in Washington’s Water Quality Standards, WAC 173-201A. For nutrient and sediment measures where there are no standard, results are expressed relative to guidelines for this eco-region. Results from these eight metrics (dissolved oxygen, pH, total phosphorus, total nitrogen, turbidity, total suspended solids, temperature, and fecal coliform bacteria) are aggregated over time to produce a single score for each sample station. In general, stations scoring 80 and above did not fail water quality standards or guidelines and are of "low concern", scores 40 to 80 indicate "moderate concern", and water quality at stations with scores below 40 are of "high concern".