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King County Washington home

Sewage releases in Seattle and King County

Short URL: kingcounty.gov/health/sewage

Sewage releases happen when sewage that hasn't been cleaned enough, or at all, gets released onto the ground, underground, or into water.

Sewage can be released from on-site sewage systems (septic systems), and public sewer systems. Since public sewer systems are much bigger than individual septic systems, sewage releases from them have a bigger impact on our environment and people's health.

Health and environmental impacts

Sewage that hasn’t been cleaned has harmful germs and chemicals that can pollute our environment and make us sick. The impacts of a sewage release depend on many factors, including how much the sewage has been cleaned, the amount of sewage, and where it is released. For example, while one gallon of sewage released hundreds of feet underwater in Puget Sound might not be a great risk to people’s health, hundreds of thousands of gallons of sewage released into a lake where many people swim is a bigger concern.

Tips to stay safe

  1. Check online for sewage releases or overflows

    For Lake Washington and Puget Sound, you can check the Combined Sewage Overflow (CSO) status map and Incident Response map to see if there have been any recent CSOs or sewage releases. Note that there could be sewage releases that aren’t listed in either of these maps, so always follow local signage as well.

  2. Look out for signs

    Don't go into a body of water if you see a beach closure or sewage/water pollution sign. This includes avoiding swimming, wading, fishing, boating, paddleboarding, kayaking, shellfish harvesting. Don't let your pets go into the water if you see a closure sign.

  3. Take action if you accidentally come in contact with sewage or contaminated water

    • Wash with soap and clean water immediately.
    • Be on the lookout for the following symptoms within two weeks: Nausea, Vomiting, Stomach Cramps, Diarrhea, Fever, Jaundice. If you have any of these symptoms, seek out medical care. You're more likely to get sick if you accidentally swallow the water.

Why do sewage releases happen?

There are many reasons sewage releases happen, and almost all are unplanned. Some of the most common reasons include:

  • A clogged or broken sewer pipe.
  • Heavy rains causing too much sewage to enter a wastewater treatment plant.

What does Public Health do to protect people's health?

We partner with Washington State Department of Ecology and the local sewer districts in King County to quickly respond to sewage releases by assessing the public health impact of the release and making recommendations for next steps. This includes recommending an area be closed, posting signs to alert people about the sewage release and collecting and analyzing water samples. Typically, signs are posted for one full week as that’s how long the bacteria last.

How is Public Health notified about sewage spills?

Typically, Public Health is notified about King County sewage spills in one or more ways:

  1. Sewer jurisdictions (often referred to as utility company or public utilities) notify us directly when they become aware of sewage spills within their jurisdictions.
  2. Washington State Department of Ecology forwards notifications to us from sewer jurisdictions or county community members about sewage spills.
  3. County community members see sewage spills and directly notify us.

For more information, including a list of sewage spills across Washington, visit Sewage Spills, WA State Ecology.