There’s an air of mystery around King County’s wastewater treatment facilities, and while it might smell like sewage, those odors could have other culprits.

Over the past several weeks, low tides and decaying seaweed have prompted an increase in calls to the Wastewater Treatment Division’s odor complaint hotlines. The calls have mainly come from residents who live near Puget Sound beaches.

Operations employees who followed up on the calls were generally able to rule out the sewer system as the cause of odors. However, the confusion is understandable because decaying seaweed produces the same smelly sulfur gas as raw sewage, according to a Washington State Department of Ecology fact sheet.

Though King County’s facilities are equipped with odor control, nuisance odors from the sewer system aren’t unheard of in the summer, when low water levels and slow flows can allow more sulfur gases to build up inside pipes.

Because King County’s Wastewater Treatment Division is committed to operating facilities that are good neighbors to surrounding communities, people can call one of three odor control hotlines to report problems.

West Point Treatment Plant (West Seattle/North Seattle)
24-hour Odor Control Hotline
206-263-3801
South Treatment Plant (South Seattle, Eastside, south King County)
24-hour Odor Control Hotline
206-684-2404

Brightwater Treatment Plant (Bothell, Woodinville, south Snohomish County)
24-hour Odor Control Hotline
206-263-9500

Additional information is also available on King County Wastewater Treatment Divisions website at www.kingcounty.gov/wtd.