Freshwater Quality
Water Quality Index
The Water Quality Index for rivers and streams combines eight measures of water quality based on monthly monitoring at individual stations across Puget Sound watersheds. Clean freshwater is vital to people and to fish and wildlife populations.
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Water Quality Index scores over 20 years for the 16 monitoring stations with the most robust water quality dataset. Few stations show a clear upward or downward trend in the freshwater Water Quality Index.

Key Indicator Results

  • Between 1997 and 2018, there was no clear upward or downward trend in the freshwater Water Quality Index (WQI). Thus, progress toward the 2020 target for this indicator is categorized as ‘not improving’.
  • Improvements have been observed in fecal coliform bacteria and total nitrogen index scores; however, trends for other measures are not significant and current conditions have remained stable due to a decrease in variability in annual WQI scores between the years.
  • The WQI indicator is below the 2020 recovery target. On average, only 28 percent of monitored stations were at or above the target value of 80 over the most recent 5-year period (2014 to 2018). This percentage is significantly lower than the baseline reference established for the 5-year period 2009-2013 (43 percent).

Contributing Partners

Recovery Target

By 2020, at least half of all monitored stations should score 80 or above on the Water Quality Index.

Methods and More Results
Last Updated
12/19/2019