State seeks public feedback on municipal stormwater permits and guidance manuals

Low-impact development includes a variety of practices that mimic or preserve natural drainage processes to manage stormwater. (Photo courtesy City of Lynnwood)

Stormwater runoff is a leading pollution threat to rivers, streams, lakes and Puget Sound in urban areas of Washington. As rain and snowmelt runs off buildings, paved roads, and parking lots, it increases in speed and volume, and can pick up pollution such as oil, fertilizers, pesticides, tire wear, trash, and pet waste. These pollutants and higher flows are carried into local water bodies, where they can harm water quality and habitat.

To manage this stormwater, Ecology has municipal stormwater permits for the state’s most populated cities and counties. The permits are aimed at reducing stormwater pollution at its source, treating it, and controlling volume and flow, so cleaner water goes into creeks, rivers, lakes, groundwater, and Puget Sound.

The regulatory approach in these permits is programmatic and a holistic approach to stormwater management, which is different from the typical water quality permit. Municipal stormwater permittees are required to develop and implement Stormwater Management programs, rather than meet a specific limit for each pollutant at the end of a pipe.

Municipal stormwater permits are divided into three categories, based on population and geography:

  • Phase I permits include incorporated cities with a population over 100,000 people and unincorporated counties with populations over 250,000 people.
  • Western Washington Phase II and Eastern Washington Phase II permits are for smaller urban areas.

Ecology said it separate the Phase II permits into East and West because of the differences in climate and rainfall patterns, and it update the permits every five years. For this permit cycle, Ecology said it is proposing a number of important updates to address specific pollutants and ensure that as communities develop, change and grow, work is being done to invest in proper stormwater management and protect water quality.

“The investments communities make into stormwater programs and infrastructure pay off. By supporting research, implementing best practices, and planning for the future, cities and counties are truly our partners in achieving cool, clean water across the state,” said Vince McGowan, Ecology’s water quality program manager

You can review all proposed changes for the permits and manuals on the department’s municipal stormwater permit reissuance webpage. Some of the proposed changes are highlighted below. Ecology is also proposing to add two municipalities to the Phase II permit based on population growth and meeting the criteria for coverage: the cities of Yelm and Ridgefield.

Responding to 6PPD

The term 6PPD stands for the chemical N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine. It’s a chemical that prevents automotive tires from degrading (i.e. breaking down) and helps them last longer. When 6PPD is exposed to air, it reacts with ozone to create 6PPD-quinone, pronounced like “qui-KNOWN,” and also referred to as 6PPD-q. This chemical is lethal to coho salmon and can contaminate water systems.

While efforts are ongoing to find a safe alternative to 6PPD in tires, Ecology said it is continuing the research and studies needed to learn how best to respond. Based on what the department has learned to date, it is proposing updates to the stormwater permit requirements and guidance in the manuals that will help reduce the amount of tire wear particles that enter the stormwater system. To learn more about all of Ecology’s work to address 6PPD, visit the 6PPD webpage.

Many of the existing best management practices (BMPs) in the permits and manuals are effective at addressing tire wear particles, including 6PPD, in stormwater runoff. The following updates will help further reduce the amount of pollution in road runoff, including tire wear particles, from reaching local waters in the near term and long term:

  • Requiring more new development and redevelopment projects to incorporate stormwater management BMPs, including Runoff Treatment and Flow Control BMPs
  • Increasing the amount of stormwater retrofits for existing development
  • Adding a street sweeping requirement
  • Requiring a Stormwater Management Action Plan, which includes planning for high priority receiving waters and identifying priority stormwater management activities, including transportation-related projects
Photo courtesy City of Mountlake Terrace

Updating requirements for new development and redevelopment statewide 

Including stormwater management BMPs, such as runoff treatment and flow control, in the planning for new development and redevelopment projects is the most cost-effective and efficient way to manage stormwater, Ecology said. The department said the updates it is proposing to these parts of the permits and SWMMs will result in more stormwater treatment.

In Western Washington, the department is proposing that the amount of new plus replaced hard surfaces be considered when determining if the project is large enough to require stormwater management BMPs for the site. Currently, Ecology only requires the amount of new hard surfaces be considered when determining if stormwater management BMPs are required.

In Eastern Washington, developers are currently only required to include stormwater management BMPs if the project disturbs one acre or more. The proposed updates to the eastern permit and manual will require the developer to consider the amount of new plus replaced hard surfaces, even if the land disturbed is less than one acre, when determining if the project is large enough to require stormwater management BMPs for the site.

These proposed updates to the new and redevelopment requirements will result in more sites incorporating stormwater management BMPs, which will result in cleaner water and healthier flow rates entering the receiving waters.

The proposed changes are different for each permit, with the specific details in the draft materials.

Increase stormwater retrofits for existing development

Existing development built before stormwater management requirements were in place continues to leave a legacy of pollution that impacts the state’s waters. The recent research findings about the toxicity of 6PPD to aquatic species highlights the need to take actions now to help to prevent further declines in fisheries and water quality.

Ecology said its stormwater retrofit proposal focuses on the Western Washington permittees:

For Phase I permittees, the department is refining the requirements for retrofits, with a focus on flow control, runoff treatment, and low impact development (LID) stormwater projects or substantial maintenance projects.  Ecology is also proposing to incentivize watershed collaboration, benefits to overburdened communities, and projects in high pollution generating transportation areas.

For Phase II Western Washington permittees, Ecology is proposing a new program as part of their permit, Stormwater Management for Existing Development. The department has designed a scaled level of effort for retrofits, to address the variety of Phase II permittees: five acres of land “managed” per 50,000 people. This program will lead to more stormwater retrofits, Ecology said.

A City of Edmonds street sweeper at work. (Photo courtesy City of Edmonds)

Prevent pollution with street sweeping 

Recent studies show the effectiveness of street sweeping as source control to prevent pollutants from entering the stormwater system. Ecology is proposing a street-sweeping requirement for public roads and parking lots in high-priority areas.

Addressing PCBs and PFAS

Significant national and statewide efforts are taking place to tackle PCBs and PFAS pollution. The proposed permit updates incorporate recent guidance on how stormwater permittees can prevent these pollutants from coming into to contact with stormwater or being discharged through municipal stormwater systems. To learn more about efforts to address these chemicals ,visit Ecology’s PFAS webpage and PCBs webpage.

Environmental justice

The municipal stormwater permits currently include requirements and guidance on identifying and engaging with overburdened communities that fall within a city or county’s permit coverage area. Ecology is proposing updates related to environmental justice in how retrofits are prioritized, how education and outreach is performed, and how public involvement programs are implemented.

Public workshops

Ecology held a series of public workshops over the past year as it developed the draft permits. Now, the agency is holding another round of workshops that include public hearings so you can provide formal oral testimony. There are four virtual workshop/hearings and two in person workshop/hearings. Full meeting details are on the permit reissuance webpage. Oral testimony provided during the hearings receives the same consideration as written comments.

Western Washington permit and manual focus
Virtual hearings

  • Sept. 18., 1:30 p.m.
  • Nov. 6, 9 a.m.

In-person hearing

  • Oct. 17, 9:30 a.m. – Lacey Community Center

Provide comment 

The draft permits and stormwater manuals are available for review and public comment from Aug. 16 through 11:59 p.m., Nov. 10. Detailed information on how to comment is on the permit reissuance webpage.

  • You can provide online comments via eComment.
  • Written comments must be postmarked by Nov. 10.
  • Please reference specific permit or manual text when possible.

— Content courtesy Washington State Department of Ecology

Leave a Reply

Your email address will not be published. Required fields are marked *

Real first and last names — as well as city of residence — are required for all commenters.
This is so we can verify your identity before approving your comment.