Toxic chemicals are concentrating in the water and entering the food chain. Low oxygen levels caused by nitrogen discharged from septic tanks, sewage treatment plants and other sources are threatening the Sound. Water quality for rivers and streams throughout Puget Sound has remained essentially unchanged for at least the past 10 years.
Only 39 percent of monitored stations were at or above the Puget Sound Partnership’s target value of 80, on average, between 2011 and 2015, which is lower than the period of 2005-2009, when 52 percent of the stations met that target value, but the difference is not significant. Six river systems—Deschutes, Nisqually, Green, Cedar, Samish, and Skokomish— had some improvements, but not enough to significantly sway the overall scores.
The hydrologic regime of rivers and streams in the Puget Sound is characterized by peak flows during the winter as a result of heavy precipitation.