Frequently Asked Questions
Preliminary Draft Western Washington Permit Language (2012)

The information on this page is outdated. The municipal stormater permit language referred to in the questions below has been revised, and the answers may or may not be accurate. This page is maintained for historical purposes only.

Please visit the the current permit page for the most up-to-date information.

Click on the questions below to see responses.

Low Impact Development (LID)

Why add LID requirements to the permits?

LID is a beneficial approach for managing stormwater runoff which, in turn, helps protect water quality and stream habitat. Preliminary draft low impact development requirements proposed for Phase I permittees and Western Washington Phase II permittees stem from appeals of the 2007 permits to the Pollution Controls Hearing Board (PCHB). The rulings by the PCHB have led Ecology to develop LID definitions, a performance standard, and feasibility criteria based on input from an advisory process.
To find out more information regarding the PCHB rulings click here:

What process did Ecology use to develop the Western Washington requirements?

After the PCHB issued rulings on the 2007 permits, Ecology used funding from USEPA Region 10 to conduct a review process to develop recommendations for LID requirements. Part of the review process included establishing two advisory committees to assist Ecology in developing LID requirements. A broad range of interests were represented, and the committee meetings were open to the public. Ecology considered the input and recommendations from the advisory process when it developed preliminary draft language for LID requirements. The LID advisory committee meeting summaries, studies, and references are available along with Ecology’s previous proposals and public comments at:

Will the LID or monitoring requirements apply to new permittees in 2012?

Ecology is evaluating a number of cities and county Urban Growth Areas for coverage under the 2012 Phase II permits. Ecology does not propose to apply the monitoring requirements under S8.C to new permittees in the next permit cycle. Ecology has not yet determined whether new permittees should be subject to the LID requirements during the next permit cycle. Considerations include the workload for local governments to update stormwater and other development codes once during this permit cycle, and then again in the following permit cycle to adopt LID requirements. On the other hand, the jurisdictions may benefit from a more gradual and incremental approach to managing runoff from new development, redevelopment and construction sites as they build their stormwater management programs. In the next permit cycle they will build programs to meet other requirements, including those for illicit discharge detection and elimination, public education, municipal operations and maintenance, and public involvement. Ecology will present its proposal on this issue in the October 2011 formal draft permit.

Western Washington LID Requirements

How is Low Impact Development defined?

Low Impact Development (LID) is a stormwater and land use management strategy that strives to mimic pre-disturbance hydrologic processes of infiltration, filtration, storage, evaporation and transpiration by emphasizing conservation, use of on-site natural features, site planning, and distributed stormwater management practices that are integrated into a project design.

What are the substantive changes to the permits for LID?

The preliminary draft permits propose at least two and in some cases, three levels of regulatory action by municipalities: 1) update stormwater and related codes to incorporate new site-level LID requirements; 2) review and revise land development-related ordinances, rules, and standards to incorporate LID principles that minimize impervious surfaces, native vegetation loss, and stormwater runoff in all types of development situations, where feasible (The intent of the revisions is to make the new LID requirements the preferred and commonly-used approach for site development); and 3) conduct hydrologic and water quality analyses to demonstrate how the municipality will maintain beneficial uses of the waters of the State in watersheds where the urban growth area will expand or where a zoning change will increase the total impervious area by five percent or more.

How will the LID requirements apply on tight soils with low infiltration rates?

Ecology recognizes that each site, city, and county is unique, and there are conditions that can make some LID techniques infeasible. In the preliminary draft Ecology is proposing infeasibility criteria for rain gardens, bioretention facilities, permeable pavements, and green roofs. If one of these infeasibility criteria applies, then the applicable LID method would not be required. Often if one LID method is not appropriate, other LID methods can still be used.

What development projects would be affected by the requirements?

In Phase I and Phase II communities, all new development and redevelopment projects resulting in 2,000 square feet, or greater, of new plus replaced hard surface area, or having a land disturbing activity of 7,000 square feet or greater would be required to meet the revised Minimum Requirement #5 (MR #5): On-site Stormwater Management. MR #5 now includes additional proposed requirements for LID based on project size, project type, and location within or outside the Urban Growth Area (UGA).

Why was the one acre threshold removed from the Phase II permit?

Ecology’s proposal to reduce the one-acre threshold is intended to prevent harm to aquatic habitat and water quality from the cumulative impacts of development on parcels smaller than one acre. If the one acre threshold were to remain in place in urban areas covered by the Phase II permit, a significant amount of development would occur without LID on smaller parcels. In most urban areas, a majority of development projects occur as infill and on project sites smaller than one acre.
To evaluate the change this would bring to Phase II communities, Ecology staff conducted a review of available municipal codes and enforceable documents in Western Washington Phase II jurisdictions in February and March of 2011. The review found a total of 73 jurisdictions, or 85%, apply stormwater standards to project sites of less than one acre. A total of 55 jurisdictions (or 64% of Phase IIs) appear to meet the thresholds in the Stormwater Management Manual for Western Washington (SWMMWW), while about 22% apply requirements at a variety of thresholds between the SWMMWW standards and the one-acre threshold. These results indicate most Phase II jurisdictions recognize the importance of managing stormwater in urban areas at sites smaller than one acre.

How would a city or county update development-related ordinances, rules, and standards?

The preliminary draft permit directs permittees to conduct and document a process similar to the steps and range of issues outlined in a document entitled: Integrating LID into Local Codes: A Guidebook for Local Governments (Puget Sound Partnership, 2011). A draft of that document is available for review starting June 1, 2011 at . Public workshops to introduce the document and receive comments from interested parties are scheduled as follows:
June 7: Tacoma, Center for Urban Waters; 326 East D. Street
June 13: Poulsbo; The New Poulsbo City Hall, 200 NE Moe Street
June 20: Mount Vernon; Public Utility District #1 of Skagit County, 1415 Freeway Drive

How would a city or county implement the watershed-scale stormwater planning requirement?

Under the proposed requirements, when a city plans an annexation, or the county a UGA expansion, of 80 acres or more in watersheds between 2 square miles and 40 square miles in size, then the permittee would have to conduct an analysis of impacts to hydrology and water quality from the proposed expansion. A similar analysis would be required in watersheds between 2 square miles and 40 square miles for a city or county taking a land use action such as zoning that increases the total watershed impervious surface area by more than five percent of the existing total impervious area of the watershed. The increases for expanded boundaries and impervious surface areas would be counted from the effective date of the permit (or the last analysis conducted in that watershed) until cumulative increases reached the threshold.
The city, or county, could reduce the impacts (or avoid the analysis, in some cases) if the proposed land use change is in an area with vegetated buffers, conservation easements, requirements for clustering and low impact development BMPs (like pervious pavement), and other measures that together reduce the impervious surface area. A city or county could plan ahead and include in the analysis additional areas of expected future expansion in the same watershed. By conducting an analysis for a larger area, or the entire watershed, the jurisdiction could reduce long-term costs and increase certainty of future land use zoning for property owners and the development community.
This proposed requirement is intended to address future land use actions that have an impact on water quality and hydrology, but is not intended to change land use decisions made in the past. However, in some cases the analysis may lead a jurisdiction to alter a past land use decision in order to reduce the impacts and avoid water quality degradation, so as to proceed with the proposed land use action.

Would watershed-scale stormwater planning requirements apply to construction projects?

Ecology does not intend this proposed requirement to apply to individual development projects. However, an individual project could trigger the analysis if the project included a change in zoning, or change in other land use regulations, which would allow an increased impervious surface area beyond five percent of the existing total impervious area of the watershed. Projects allowed under previous zoning would not count toward the threshold for watershed-scale analysis. However, the LID site and subdivision-scale requirements adopted under the permit would apply to the project.

Would watershed-scale planning be required?

No, the proposed requirement for watershed-scale stormwater planning does not require permittees to develop a watershed plan. However, Ecology is proposing triggers for watershed analysis based on the percent of impervious area or based on an expansion of a city or UGA boundary by 80 or more acres within watersheds of approximately 2 square miles to 40 square miles in size.
The analysis would require an assessment of the hydrologic and water quality impacts from upstream and upon areas downstream of the proposed land use action. The assessment would consider impacts under existing land use regulations in the area outside its jurisdiction. In some cases, a city or county might have authority over the entire watershed, but in many cases the watershed extends into another jurisdiction.
The proposed requirement does not mandate cooperation among jurisdictions to develop a watershed plan, and expects that measures for limiting harm from development will be based on actions within the area under the jurisdiction’s authority. Ecology does not propose to require that jurisdictions cooperate with each other in the analysis, but encourages such cooperation where it occurs. For example, a county proposal to increase the unincorporated UGA is often done with agreement of a city, and together they might undertake an analysis of a watershed that they have identified as suitable for future urban development.

Will Ecology provide tools, guidance, and examples for watershed-scale stormwater planning?

Ecology is working with several jurisdictions on watershed-scale projects to model the hydrologic and water quality impacts of development. These projects vary in the existing level of urbanization, watershed size, and the models and methods being applied. Ecology plans to provide guidance, templates, and examples from these projects. We will also look for grant funding for additional projects, and for opportunities to integrate TMDL (Total Maximum Daily Load) studies and water cleanup plans to advance and support permittee efforts.

LID in Eastern Washington

Should Eastern Washington expect to have similar LID requirements?

Eastern Washington has unique climate conditions, geology, soils, and stormwater management approaches that differ greatly from those in western Washington. Therefore, LID requirements and approaches will be different from those proposed in the draft Phase I and WWA Phase II permits. Many Eastern Washington permittees are already taking advantage of LID principles such as requiring all stormwater to be infiltrated on-site and full dispersion BMPs. Ecology is initiating a series of meetings with permittees and interested parties to develop recommendations for LID requirements for eastern Washington.

What process will Ecology use to develop the Eastern Washington requirements?

Ecology will rely on input from discussions with permittees and others in eastern Washington during summer 2011 to develop draft requirements for LID for the October 2011 formal draft permit. The discussions may consider steps to advance LID such as evaluation of a hydrologic performance standard with feasibility criteria, a list of acceptable BMPs, and a path forward both inside and outside of the permit structure to develop an LID manual, guidance, and research regarding the performance of LID BMPs in soils and precipitation patterns of different sub-regions of the eastern Washington landscape. Ecology invites comments during this informal review period to suggest topics for discussion.

Monitoring Language

What jurisdictions are affected by the proposed stormwater monitoring requirements?

Ecology is proposing preliminary draft permit language for monitoring requirements in three areas of Washington State:
Western Washington permittees include those in Puget Sound and those in southwest Washington. In Puget Sound, the current municipal stormwater permits cover 5 Phase I and 76 Phase II cities and counties and the Ports of Tacoma and Seattle. In southwest Washington, the current permits cover 1 Phase I county and 9 Phase II cities and counties. In eastern Washington, the current permit covers 24 Phase II cities and counties.
The Washington State Department of Transportation would be affected when Ecology reissues its permit, which is on a different five-year cycle.

What are the proposed stormwater monitoring requirements?

The preliminary draft language proposes a collaborative, regional approach to stormwater monitoring throughout western Washington. The proposed structure includes a coordinated monitoring program based on shared costs among permittees, with Ecology acting as the service provider to administer contracts. Permittees would participate in a formal oversight committee. This proposed approach removes specific monitoring requirements from the permits and relieves individual permittees of the obligation to individually conduct monitoring activities.
In southwest Washington, permittees and others are working to develop an alternate proposal for monitoring water bodies that receive stormwater discharges. For eastern Washington, Ecology proposes a stakeholder process to develop a regional monitoring program and a framework to administer it. The preliminary draft language includes default proposals for monitoring in southwest and eastern Washington. However, Ecology anticipates that the stakeholder processes will produce appropriate proposals for these regions’ unique characteristics.

How did Ecology come up with the proposed stormwater monitoring requirements?

The overall approach for western Washington was developed in a two-year stakeholder process involving federal, tribal, state and local government, business, environmental, agriculture and research interests at the request of the Puget Sound Partnership and Ecology. The Stormwater Work Group (SWG) recommended a comprehensive monitoring approach for the next NPDES municipal stormwater permits in Puget Sound. Ecology is proposing to expand some, but not all, of the Puget Sound recommendations throughout western Washington. Ecology is proposing a similar process be used to develop a monitoring program of receiving waters for southwest Washington and an overall monitoring program for eastern Washington.

What are the implications for local governments?

All local governments in Washington will benefit from the information generated by regional monitoring. In western Washington, Phase I and II permittees would be required to equitably pay into a collective fund for the regional monitoring program instead of being required to conduct individual jurisdiction monitoring programs. This regional monitoring program would not replace individual jurisdiction sampling for illicit discharge detection activities, or sampling conducted to further the goals of an applicable TMDL or other local water quality investigation. Permittees and others with monitoring capacity would have the opportunity to receive funds to conduct parts of the regional monitoring program.

What process did the SWG use in developing the plan?

Ecology allowed the SWG to use a great deal of flexibility to create a regional approach to stormwater monitoring. Municipal participants knew there would be monitoring in the next Phase II municipal stormwater permits and wanted to avoid the potential requirement to replicate current Phase I monitoring. The SWG spent almost two years developing a scientific framework and an implementation plan for regional monitoring. The process included talking to people who have done this and succeeded elsewhere around the country, two public comment periods, and three large regional workshops.
Ecology is offering a similar level of flexibility and responsibility to permittees and stakeholders in southwest and eastern Washington in developing their monitoring proposals.

What are the advantages to local governments of adopting this regional approach?

The regional stormwater monitoring program will help evaluate whether stormwater management actions, in aggregate, are resulting in statistically significant improvements surface water quality. In addition, the plan will:

Why is Ecology recommended as the initial administrator of the funds?

The SWG considered numerous potential entities that might serve this important role and ultimately concluded that Ecology provides the only viable option at this time because Ecology is the only entity with the administrative capacity and willingness to assume this role and responsibilities for the next municipal stormwater permit. A different organization might be chosen for subsequent permits, or for the southwest or eastern Washington programs.

When do the permit requirements go into effect?

The proposed stormwater monitoring requirements would go into effect after the next NPDES municipal stormwater permits are issued. Phase I permittees would contribute funds in the first year new permits are effective. Phase II permittees in western Washington would contribute funds in the second year the new permits are effective. During the second year the new permits are effective, the program would begin to conduct effectiveness studies. The second and third years of the new permit would also be dedicated to preparing for monitoring receiving waters in the fourth.
Permittees in eastern Washington would contribute funds to begin effectiveness studies in the third year the new permits are effective. They would contribute funds to prepare for receiving water monitoring during the fourth year the new permits are effective, and to fully implement the program during the fifth year the new permits are effective.

What are the next steps?

Ecology is releasing preliminary draft permit monitoring language in May 2011 for public review and comment. The public comment on formal draft permits will begin in October 2011. The final permits are expected to be issued in July 2012.

Back to Top