Purple Sulfur Bacteria Return to Cottonwood Beach

Along with the warm, sunny weather, an unusual and stinky phenomena has returned to Birch Bay this summer. Beach walkers have to navigate a zone of "pink gooey stuff" coating the upper reaches of Cottonwood Beach. The pink stuff is purple sulfur bacteria. This type of bacteria thrive in water with low levels of dissolved oxygen and high levels of sulfur. These conditions are promoting the bacteria's growth this summer. A combination of warm water and decaying algae and eelgrass create the low dissolved oxygen, or anoxic, conditions in the bay. The rotten egg smell comes from hydrogen sulfide, another by-product of decaying alage. Sulfur bacteria can use hydrogen sulfide as a food source. Some people may experience irritated eyes, nose, or throat; headaches; or nausea from exposure to the hydrogen sulfide gas. If you experience any of these symptoms leave the area. If you have questions please contact Ingrid Enschede at (360) 715-7450 x50787.

The Washington State Department of Ecology's publication Focus on Saltwater Beach Odors is a good reference for more information on the source of beach smells, possible health concerns, and connections to nutrient pollution in stormwater.