Fixing Mistakes of the Past
Over the past century, we covered our communities with pavement and hard surfaces in the form of roads, sidewalks, parking lots, roofs, and more. New rules to reduce stormwater pollution from new construction projects generally don’t apply to existing hard surfaces. How can we prevent these surfaces from becoming a pathway for pollution into the Sound?
Many residents in our region have stepped up and taken individual action to filter, slow, and collect stormwater, by installing rain gardens and cisterns on their property and in their communities. These mitigation efforts reduce the amount of polluted stormwater flowing into our waterways. You can check out progress voluntarily reported by community members, here. As of December 2021, community members reported 11,007 unique stormwater projects throughout the Puget Sound region. Unfortunately, the biggest infrastructure projects with the biggest footprint—including roads, bridges, and public facilities—are owned or controlled by municipalities, not community members.
The Washington State Department of Ecology (Ecology) requires our most populous cities and counties to install stormwater retrofits to treat or control stormwater from existing development. This requirement has been in place since 1995. However, these requirements only apply to “Phase I” Permittees: Seattle, King County, Snohomish County, Pierce County, Tacoma, and Clark County. Today, many other municipal Permittees are just as populous, and just as developed, as these Phase I Permittees. Yet they lack retrofit requirements.
In 2020, Puget Soundkeeper (PSK) and Washington Environmental Council (WEC) realized that our region lacked a comprehensive assessment and public report about municipal progress toward stormwater retrofit investments. We collaborated to research and report on how many, and where, our most populous cities and counties have installed Structural Stormwater Controls—stormwater investments including stormwater retrofits—from 2007 until today.
Who Did We Assess?
We looked at five Phase I Permittees: Seattle, Tacoma, King County, Pierce County, and Snohomish County; and seven Phase II Permittees: Bellevue, Everett, Kent, Federal Way, Renton, Thurston County, and Kitsap County.
Find out more about our methodology.
The five Phase I’s have had legal requirements to install stormwater retrofits since 1995. These projects are required as part of Phase I Permittees’ Structural Stormwater Control (SSC) Program. The seven Phase II cities and counties we looked at meet or exceed the population thresholds defining Phase I’s. To date, they do not have any retrofit requirements.
In other words, the Phase II Permittees have population, development, and resource-use impact comparable to Phase I Permittees yet lack the same level of regulation.
If your city or county was not included in our assessment and you want to find out what your community has done to control polluted stormwater, you can click here to find your council member’s information, and reach out to ask.
What Did We Discover?
Stormwater remains the primary source of toxic pollution to Puget Sound. We can implement proven methods to stop it. We must stop using harmful chemicals and stop dumping toxic pollution into our environment. We must also implement more LID and stormwater retrofits to treat and control stormwater from both new development and existing development. And we must clean up sources of legacy pollution.
451 Total Projects Identified, 2007 – 2021
As a result of our research, we identified 451 total qualifying Structural Stormwater Control (SSC) projects that were planned or completed by the twelve most populous Puget Sound Permittees we assessed.
Municipalities can review our Decision Tool to find out how we assessed qualifying SSCs.
The five Phase I’s reviewed include jurisdictions that cover almost half of the Puget Sound basin or drainage area. Over the 15-year period we studied, these Phase I municipalities reported 268 (qualifying) SSCs, which averages fewer than 18 total projects per year. In comparison, the seven Phase II’s we reviewed (which lack an SSC requirement) completed 183 SSC projects, or a little more than 12 total projects per year.
The 11 types of qualifying Structural Stormwater Controls—the projects that municipalities must complete in order to comply with their permit requirements—can be categorized into four function types: Flow Control, Toxics Reduction, Restoring Ecosystem Function, and Maintenance and Prevention.
SSC projects in the Flow Control and Toxics Reduction function types include projects that actually retrofit the built environment to treat and control stormwater pollution. SSC projects in the Restoring Ecosystem Function and Maintenance and Prevention function types are also valuable and can protect clean water, but due to their nature these SSC projects rarely retrofit the built environment. Instead, they often preserve less developed areas.
Visit our SSC Glossary of Terms to learn more about these four different function types of local stormwater pollution controls.
Toxics Reduction function type projects, including runoff treatment projects like bioretention, have the ability to save coho salmon by filtering out toxic chemicals including 6PPD-quinone. Of the Phase I’s we studied, Seattle completed the most Toxics Reduction projects (14 out of 25); of the Phase II’s we studied, Kitsap County completed the most Toxics Reduction projects (15 out of 29).
How many of the SSC projects have toxic reduction functions that can save salmon? These graphs show the 451 SSC projects we identified compared with the number of toxics reduction SSCs that can filter out pollutants like 6PPD-quinone and save salmon. Our most vulnerable salmon populations should be prioritized!

You can find out more about the GIS maps we used to perform these analyses, and see all the SSC projects mapped, in our Storymap.
We found that permittees could do a better job of proactively planning and implementing stormwater retrofits in dense, highly urbanized areas; in areas with heavily impacted salmon streams; and in areas with and greater environmental health disparities.
PSK and WEC believe that investments in these areas will yield more meaningful benefits by improving health outcomes for the most at-risk people and wildlife.
Our Conclusions and Recommendations for the Department of Ecology
As a result of our research, we found that:
- Some Phase II’s are doing more projects than Phase I’s—despite having no requirements to do any
- Some permittees are reporting projects with little or no stormwater nexus to comply with Clean Water Act requirements, and
- Reporting requirements lack sufficient context needed to determine if water quality is actually improving
As such, we recommend that the Department of Ecology strengthen the municipal general stormwater permits to:
- Require Phase II’s to implement SSCs
- Require Permittees to prioritize retrofit projects in the built environment, in areas with a high or medium prevalence of Urban Runoff Mortality Syndrome (URMS), and in overburdened communities
- Base Clean Water Act requirements for both existing and future development on a proportionate approach, where performance is evaluated based on whether each Permittee has restored or protected a required proportion or quantity of waters in their jurisdiction each Permit cycle
Permittees have invested in stormwater infrastructure for decades, and individual SSC projects are very valuable. Despite this work, we found no evidence that current regulatory requirements or approaches are making a dent on overall Puget Sound water quality.
This is not due to lack of effort, or because these projects made no improvement to water quality locally. There have been many small successes. Our municipalities have done a good job juggling competing priorities with limited resources.
Preventing and treating stormwater pollution requires more funding, and political and regulatory support in the form of a clear mandate to save Puget Sound. The Department of Ecology must also strengthen existing Clean Water Act Permit requirements by setting out a clear path to restore Puget Sound. The proven effectiveness of LID and Green Stormwater Infrastructure will be key in accomplishing this goal.
To learn more about our findings and conclusions, explore the Storymap and Report. You can help by reaching out to your local elected officials today, to express your concerns and interest in local stormwater pollution controls.