Recent assessments of dissolved oxygen in Puget Sound waters have highlighted a significant decrease in levels, particularly in the deep basins during summer months. This decline poses serious risks to the region’s unique marine ecosystems, affecting species such as Pacific salmon, Dungeness crabs, and bottom-dwelling invertebrates. Low oxygen, or hypoxia, has been linked to increased algal blooms fueled by nutrient runoff from urban and agricultural areas, which exacerbate microbial activity and oxygen consumption in the water column. Scientists emphasize that these changes create “dead zones” where marine life struggles to survive or is forced to migrate, disrupting food webs and commercial fisheries alike.

The Department of Ecology’s ongoing monitoring program highlights several key factors…