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Reducing stormwater pollution, the growing threat to water quality in King County

Reducing stormwater pollution, the growing threat to water quality in King County

Polluted stormwater – runoff that occurs during rainfall – is perhaps the biggest threat to water quality today in King County.

It carries toxins – motor oil, metals, pesticides, fertilizer, pet waste, and more – directly into streams, rivers, and Puget Sound. It’s contributing to the dramatic decline in native salmon and is threatening the survival of southern resident orcas.

And the threat to water quality is accelerating.

We are experiencing more severe rainstorms as the result of climate change, and more of that rain is falling on impervious surfaces – roads, parking lots, and rooftops – which is pushing more toxins into waterways.

At the direction of Executive Constantine, King County scientists are working with partners to determine the most effective way to reduce stormwater pollution.

It’s a key part of Clean Water Healthy Habitat, an initiative he launched to ensure that we make the right investment to achieve the best results.

Why polluted stormwater is a growing threat to water quality

Rain is naturally filtered when it falls on undeveloped land.

When rain falls on undeveloped land, the stormwater is naturally filtered

As our region continues to grow, more rain is falling on paved surfaces, pushing more pollutants directly into waterways.

Some pollution sources: motor oil and metals, yard chemicals and pet waste

At one time, sewage was the biggest threat to water quality in King County. But over the past six decades, we’ve built a regional system that can treat more than 66 billion gallons of wastewater and stormwater each year.

66 billions of gallons of storwater and wastewater are treated and discharged into Puget Sound

The far bigger threat today is the estimated 118 billion gallons of polluted stormwater that doesn’t get treated, carrying toxins into rivers, lakes, and Puget Sound, threatening survival of native salmon and southern resident orcas.

118 billion gallons of polluted stormwater flows untreated into Puget Sound, including 0.6 billion gallons from combined sewer overflows

How you can help

There are personal actions you can take to help keep polluted stormwater out of our waterways.

Help keep stormwater clean by maintaining your car: fix oil leaks and get emissions checked and repaired
Maintain your car: Fix oil leaks and reduce emissions
Help keep stormwater clean: Forego fertilizers and pesticides and practice natural lawn care instead
Practice natural yard care
Help keep stormwater clean: wash your vehicle at a car wash or on the lawn instead of the street or driveway
Wash your car at a commercial carwash
Help keep stormwater clean: pick up pet waste and dispose of it in the trash
Pick up pet waste
King County Executive
Dow Constantine
Dow constantine portrait

Read the Executive's biography