The Phase I Municipal Stormwater Permit (special condition S5.C.5.a) and the Western Washington Phase II Municipal Stormwater Permit (WWA Phase II Permit) (special condition S5.C.6.a) require permitted cities and counties to establish enforceable programs to manage stormwater from new development, redevelopment, and construction activities.
There are two parts to the enforceable program requirement:
The first part of the program must describe the minimum technical requirements, thresholds, definitions, adjustments, and variance criteria to be used for new development, redevelopment, and construction sites.
From S5.C.6.b.i of the Wester Washington Phase II Permit, an ordinance or other enforceable mechanism must include:
"The Minimum Requirements, thresholds, and definitions in Appendix 1, or the 2013 Appendix 1 amended to include the changes identified in Appendix 10, or Phase I program approved by Ecology and amended to include Appendix 10, for new development, redevelopment, and construction sites."
Both permits contain an identical Appendix 1, including a basin planning option (Section 7), which permittees may use (with Ecology’s approval) to tailor certain minimum requirements or demonstrate an equivalent level of protection through the use of regional facilities.
The second part of the program required in both permits is the implementation of site planning requirements; Best Management Practice (BMP) selection, design, and infeasibility criteria; BMP limitations; as well as Low Impact Development (LID) competing needs criteria.
These components work together to protect water quality, reduce the discharge of pollutants to the Maximum Extent Practicable (MEP) and satisfy Washington state requirements for applying AKART.
From S5.C.6.b.ii of the WWA Phase II Permit:
"The local requirements shall include the following requirements, limitations, and criteria that, when used to implement the minimum requirements in Appendix 1 (or program approved by Ecology under the 2019 Phase I Permit) will protect water quality, reduce the discharge of pollutants to the MEP, and satisfy the State requirement under Chapter 90.48 RCW to apply AKART prior to discharge:
- Site planning requirements
- BMP selection criteria
- BMP design criteria
- BMP infeasibility criteria
- LID competing needs criteria
- BMP limitations"
The primary distinction between the two permits is that Phase I permittees must submit their draft enforceable requirements, technical standards, and manuals to Ecology for review and approval, whereas Phase II permittees are not given the option to do so.
The Phase I process is generally referred to as an “equivalency review.” During this review, we evaluate each Phase I program for its functional equivalency to the requirements described in Appendix 1 and the relevant portions of Ecology’s Stormwater Management Manual for Western Washington (SWMMWW). We do not have the capacity to review Phase II programs in detail, and thus rely on the Phase II Permit and Appendix 1 to ensure the minimum requirements, thresholds, and definitions are consistently applied to projects in Phase II coverage areas.
Western Washington Phase II cities and counties essentially have three compliance pathways for implementing the relevant requirements of S5.C.6:
- Adopt the minimum technical requirements, thresholds, definitions, adjustment and variance criteria found in Appendix 1, or
- Develop and adopt tailored minimum technical requirements and implementing BMPs* based on an Ecology-approved basin plan or other similar water quality and quantity planning effort that provides equal or similar protection of receiving waters and equal or similar levels of pollutant control as compared to Appendix 1. For this option, Ecology must review and approve the basin plan or similar planning effort prior to the permittee’s adoption and use of the tailored requirements, or
- Adopt the minimum technical requirements, thresholds, definitions, adjustment and variance criteria found in an Ecology-approved equivalent Phase I program.
*Note that adjustment and variance criteria as written in Appendix 1 or equivalent to those in Appendix 1 must be adopted. It is unlikely that an Ecology-approved basin plan would justify changes to the Appendix 1 adjustment and variance criteria.
Special Condition S5.C.6.b.ii requires permittees to develop site planning requirements, BMP selection, design and infeasibility criteria, BMP limitations, and LID competing needs criteria that when used to implement the minimum technical requirements of Appendix 1, protect water quality, reduce the discharge of pollutants to the MEP, and satisfy AKART prior to discharge.
Documenting the pathway to compliance
Permittees must document that their programs meet these objectives through one of the following compliance pathways:
- Choose and cite the requirements, limitations, and criteria in the SWMMWW, or
- Choose and cite the requirements, limitations, and criteria in an Ecology-approved Phase I program, or
- Develop and adopt requirements, limitations, and criteria addressing S5.C.4.a.ii.(a)-(f) that protects water quality, reduces the discharge of pollutants to the MEP, and satisfies Washington state requirements for applying AKART. For this option, the burden is on the permittee to document how the local program accomplishes these objectives prior to discharge.
Combining different manuals
It is important to keep in mind that a Phase II permittee may only establish alternative requirements to the minimum technical requirements, thresholds, and definitions contained in Appendix 1 (S5.c.6.b.i) through adoption of an Ecology-approved basin plan (Section 7 of Appendix 1) or through the adoption of a single Ecology-approved Phase I program. Some Phase II permittees have expressed interest in selecting specific components of several different Phase I equivalent programs and/or the SWMMWW, and combining these requirements into a unique local program.
We expect that Phase II permittees adopting an Ecology-approved Phase I program (i.e., in lieu of Appendix 1) are also adopting the associated site planning requirements, BMP selection, design, infeasibility criteria and limitations, and LID competing needs criteria from that same Ecology-approved Phase I program. If a Phase I program has received our approval for alternatives to the minimum technical requirements, thresholds, definitions, adjustment and variance criteria in Appendix 1, such alternatives are only appropriate when implemented with the requirements, limitations and criteria addressing S5.C.6.b.ii.(a)-(f) that are part of that Ecology-approved program, and any additional conditions that we place on such an approval.
If a Phase II permittee chooses to select different BMP limitations or criteria, or site planning requirements from several different Phase I programs, the onus is on the permittee to document how this composite manual meets the permit requirements as described above. This approach is essentially a version of the third compliance pathway listed above for S5.C.6.b.ii. In this case, a permittee cannot rely on our determination of equivalency associated with the Phase I programs because our equivalency determination is based on a review of the individual Phase I program as a whole.
It is incorrect to assume that individual elements of approved equivalent Phase I programs can be isolated, recombined, and still be equivalent to Appendix 1 and the SWMMWW. Permittees are cautioned that this practice may create potential liability. Furthermore, it may be inappropriate to adopt a Phase I program designed to address specific general conditions in a Phase I community (e.g., highly urbanized, fully built-out city) in a jurisdictions with significantly different characteristics (large-lot suburbs at the fringe of an urbanized area).
Here are a few examples of how this may happen:
- Specific elements of a Phase I equivalent manual may be tied to other specific program elements in order to make the full suite of conditions/requirements equivalent to the minimum requirements of the permit (as described in Appendix 1 and as referenced to the SWMMWW). Selecting one program element without the others may create a situation where a requirement does not meet MEP or AKART.
- Some requirements may exist in sections of local code outside of the stormwater code. For example, requirements associated with Appendix 1, Minimum Requirement #8, Wetlands, may exist in the Phase I permittee’s critical areas code and not in their stormwater code.
- Specific procedural requirements or steps in a Phase I program may not be available to another jurisdiction. For example, Washington State Department of Transportation’s (WSDOT) Highway Runoff Manual contains provisions for project-specific alternatives subject to approval by a “Demonstrative Approach Team.” This procedural requirement is not available to Phase I or Phase II cities and counties.
- Some aspects of a Phase I program may be based on the conditions present in that jurisdiction. For example, a Phase I program designed to address redevelopment inside the Urban Growth Boundary (UGA) will not be appropriate for new development outside the UGA.
Without our approval and an associated determination of equivalency of a local code and manual, the local jurisdiction must rely on its own justification and documentation that the local program meets the permit requirements. Ecology, EPA, or a third party may review such documentation to evaluate compliance with the permit.
We encourage any permittee who is considering using some element(s) of an Ecology-approved equivalent Phase I program to review the comments and resolution documentation associated with that Phase I program review. These materials will be available on the Phase I equivalent manual page Phase I equivalent manual page when they are completed. Note that a Phase I program is not considered “equivalent” until after we have modified the Phase I permit (Appendix 10) following public review and comment. We may consider the program “approvable” until such time as the permit modification is completed and the determination of “equivalent” can be made.
Washington Department of Transportation’s Highway Runoff Manual (HRM)
We have determined the HRM to be equivalent to both of Ecology’s Western and Eastern Washington stormwater management manuals for minimum design requirements and best management practices for public road projects. Permittees may adopt and employ these equivalent sections (only) for use within their jurisdictions.
Please note that there are additional provisions (or exemptions) in the HRM that apply only to WSDOT and are not appropriate for local governments to follow and implement. The HRM was revised and updated on April 30, 2019; the conditions of equivalency for the HRM will be described in the Phase I Municipal Stormwater Permit, Appendix 10, and on the website cited above.