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Protecting Seattle’s Waterways

Sewage Overflow Prevention

Lake Union

Seattle waterways will benefit from upcoming projects to prevent sewage overflows and polluted stormwater runoff.

Every year, rain washes millions of gallons of untreated sewage and stormwater into the city’s waterways, threatening human and aquatic health and our quality of life. In 2012, more than 154 million gallons of raw sewage and stormwater spilled into Seattle’s creeks, lakes, the Ship Canal, the Duwamish River, and Elliott Bay. These combined sewage overflows (CSOs) create significant health and environmental risks.

The Plan to Protect Seattle's Waterways

The City of Seattle negotiated a first-of-its-kind agreement that will prevent sewage overflows and allow Seattle Public Utilities to use the most cost-effective projects that provide the most benefit to our waterways.

More detailed information:

Over the next 12 years, Seattle is expected to spend about $500 million on projects to implement the Plan to Protect Seattle's Waterways. Funding these water-quality improvements is expected to increase a typical single-family customer's drainage and wastewater bill by an estimated $58.76 per year by 2025.

The plan is also expected to save customers approximately $375 million in future operating and maintenance costs over that same time because Seattle Public Utilities (SPU) has been able to demonstrate that the way it inspects and maintains the sewer system has significantly reduced the risk of pipe breaks and sewage spills.