Wastewater

Scientists at the Washington Department of Ecology along with many other researchers have spent years studying and debating the problem of low oxygen in Puget Sound. Now, many new developments — technical, scientific and legal — are reaching a critical stage and setting up a framework to make some major decisions. This four-part series was originally published in the Puget Sound Institute blog and looks back on how we have reached our present condition, including a consideration of possible solutions. Subsequent parts of the series are available through a link at the conclusion of this article.

State agencies tracking pollution levels in Puget Sound have discovered traces of oxycodone in the tissues of native bay mussels (Mytilus trossulus) from Seattle and Bremerton area harbors. The findings were presented at the 2018 Salish Sea Ecosystem Conference in Seattle. 

As the region's population grows, scientists say we can expect to see increasing amounts of nitrogen and other elements flowing into Puget Sound. Known as “nutrients” these elements are naturally occurring and even necessary for life, but officials worry that nutrients from wastewater and other human sources are tipping the balance. That could mean big problems for fish and other marine life, gradually depleting the water of oxygen and altering the food web.

Drugs like Prozac and cocaine have been showing up in the region’s salmon. But these are just some of the potentially thousands of different man-made chemicals that escape into the Salish Sea every day, from pharmaceuticals to industrial compounds. Now the race is on to identify which ones pose the greatest dangers.

A 2016 paper in Environmental Pollution identifies dozens of pharmaceuticals and other compounds that are accumulating in Puget Sound fish such as salmon.

A 2025 report from the University of Washington Puget Sound Institute identifies and evaluates potential strategies for addressing environmental concerns over nutrients and dissolved oxygen in Puget Sound.