Skip to content
Menu

Document Author: WA Department of Ecology

Stormwater Management Cation Planning Guidance for Phase I and Phase II NPDES permits

Summary: Western Washington Stormwater Management Action Planning Guidance, comprehensive stormwater planning, watershed planning,

Stormwater Management Action
Planning Guidance
Phase I and Western Washington Phase II
Municipal Stormwater Permits
August 2019
Publication 19-10-010
Stormwater Management Action Planning Guidance
Page i
Publication No. 19-10-010
Publication and Contact Information
This document is available on the Department of Ecology’s website at:
https://fortress.wa.gov/ecy/publications/summarypages/1910010.html
For more information contact:
Water Quality Program
P.O. Box 47600
Olympia, WA 98504-7600
Phone: 360-407-6600
Washington State Department of Ecology — www.ecology.wa.gov
Headquarters, Olympia
360-407-6000
Northwest Regional Office, Bellevue
425-649-7000
Southwest Regional Office, Olympia
360-407-6300
Central Regional Office, Union Gap
509-575-2490
Eastern Regional Office, Spokane
509-329-3400
To request ADA accommodation including materials in a format for the visually impaired, call Ecology
at 360-407-6600 or visit https://ecology.wa.gov/accessibility. People with impaired hearing may call
Washington Relay Service at 711. People with speech disability may call TTY at 877-833-6341.
Stormwater Management Action
Planning Guidance
Phase I and Western Washington Phase II
Municipal Stormwater Permits
Water Quality Program
Washington State Department of Ecology
Olympia, Washington
Stormwater Management Action Planning Guidance
Page iii
Publication No. 19-10-010
This page intentionally left blank
Stormwater Management Action Planning Guidance
Page iv
Publication No. 19-10-010
Table of Contents
Publication and Contact Information ………………………………………………………………………………………….. i
Purpose and Context of this Document ………………………………………………………………………………………. 1
Introduction …………………………………………………………………………………………………………………………………….. 1
Summary of the Process Described in this Document …………………………………………………………….. 2
Receiving Water Conditions Assessment …………………………………………………………………………………… 3
Step 1: Delineate Basins and Identify Receiving Waters …………………………………………………….. 3
Step 2: Assess Receiving Water Conditions …………………………………………………………………………… 5
Step 3: Assess Stormwater Management Influence ……………………………………………………………… 7
Step 4: Assess Relative Conditions and Contributions ………………………………………………………… 8
Receiving Water Prioritization …………………………………………………………………………………………………….. 9
Stormwater Management Action Plan ……………………………………………………………………………………… 11
The need for and most beneficial placement of stormwater
facility retrofits …………………………………………………………………………………………………………………………. 13
Land management/development strategies identified for
water quality management …………………………………………………………………………………………………….. 13
Targeted or customized implementation of stormwater
management actions ……………………………………………………………………………………………………………….. 14
Proposed implementation schedule and budget sources …………………………………………………. 14
Process to adaptively manage the plan ……………………………………………………………………………….. 15
Conclusion …………………………………………………………………………………………………………………………………….. 15
References …………………………………………………………………………………………………………………………………….. 16
Stormwater Management Action Planning Guidance
Page v
Publication No. 19-10-010
This page is intentionally left blank
Stormwater Management Action Planning Guidance
Page 1
Publication No. 19-10-010
Purpose and Context of this Document
This document provides guidance to jurisdictions implementing Stormwater Management Action
Planning (SMAP) as required in the 2019 Phase I and Western Washington Phase II Municipal
Stormwater Permits (the Permits). This document is organized according to the Phase II Permit language
in S5.C.1.d, and provides Ecology’s guidance for meeting the Permit requirements. This document is not
meant to constrain or prescribe the approach that will be taken by every jurisdiction covered by the
Permit.
For S5.C.6.d, Phase I Permittees that elect to develop a SMAP for a single sub-basin or catchment area
located within the watershed-scale stormwater plans developed during the 2013 Permit term must
consider the guidance in the SMAP section beginning on p. 11 of this document. A Phase I County that
chooses to prepare a SMAP for a basin that was not selected for their watershed-scale stormwater plan
must consider the whole of this guidance document.
Introduction
There are many ways to successfully approach comprehensive stormwater planning in general, and
many ways to approach the specific steps required by the Permit and in this document in particular.
Ecology recognizes that many jurisdictions are already actively planning stormwater investments and
actions to accommodate future growth in a way that minimizes impacts to receiving waters and
designated uses. Jurisdiction staff responsible for developing a SMAP may, and should, coordinate with
other local planning efforts and use and leverage those efforts to produce the permit-required
deliverables. Some jurisdictions may simply need to add a subset of the steps required by the permit
and described below to an existing planning effort. Others may have a plan or process underway that
completely meets Ecology’s goals and guidance for meeting the Permit requirements.
In addition to this document, Permittees should be familiar with the following references in order to
understand and meet the requirements and the goals for the SMAP process:
Building Cities in the Rain (BCitR, Commerce 2016)
The following subsections in the Permit Fact Sheet (Ecology 2018):
In Section 3.1: “The Stormwater Problem”
In Section 3.2.1: “Phase I Counties’ Watershed Modeling and Planning”; “Stormwater Action
Monitoring”; “Toxic Loading Study for Puget Sound”; and “Phase I Stormwater Outfall
Monitoring Data”
In Section 6.5: “Comprehensive Planning for Municipal Stormwater. Western WA only
(Phase I S.5.C.6; WWA Phase II: S5.C.1.)”
The Permit requires a planning approach that emphasizes protection of designated uses and
improvements to receiving water quality and habitat under both existing and anticipated future
developed conditions. Many of the steps below are explained in detail in BCitR. SMAP is focused on
addressing impacts from the cumulative development in a watershed rather than on single site or
subdivision impacts. SMAP helps to answer these two important questions:
Stormwater Management Action Planning Guidance
Page 2
Publication No. 19-10-010
1) How can we most strategically address existing stormwater problems?
2) How can we meet our future population and density targets while also protecting and
improving conditions in receiving waters?
A successful SMAP strategically identifies approaches – in addition to current requirements of the
Permit – to accommodate future growth and development while preventing water quality degradation
and/or improving conditions in receiving waters harmed by past development.
Please note that in this document, “SMAP” is used as either a verb, for the planning; or as a noun, for
the resulting plan.
Summary of the Process Described in this Document
To successfully complete a SMAP, Permittees will use available information and professional judgment
to:
Assess Receiving Water Conditions (section beginning on p. 3). In this step you will become
acquainted with all of your MS4 receiving waters by:
1. Delineating all of the basins in your jurisdiction and identifying the receiving waters with
total watershed areas between one square mile and about 20 square miles (p. 3).
2. Doing a rapid assessment of existing information about conditions in your receiving waters
(p. 5).
3. Assessing the relative current and potential influence of your MS4 on each of your
receiving waters (p. 7).
4. Putting all of this information together to narrow your list of receiving waters to a list that
makes sense for prioritization in a public process (p. 8).
Prioritize your narrowed list of receiving waters (section beginning on p. 9). In this step you will
gather public input, build support for your SMAP, and select the receiving water and the sub-
basin or catchment area(s) where SMAP best suits your MS4.
Develop a SMAP for the selected catchment area (section beginning on p. 11). In this step you
will:
o Identify specific stormwater management actions to protect water quality in your selected
receiving water, and
o Determine an appropriate schedule and budget sources for implementing the activities and
projects you have identified.
The remaining sections of this document describe each of these steps in more detail. Although these
steps are presented in consecutive order, they may be implemented concurrently if that makes sense to
the jurisdiction. Throughout this process, Permittees should follow a transparent process that informs
and seeks input from stakeholders and residents.
Stormwater Management Action Planning Guidance
Page 3
Publication No. 19-10-010
Receiving Water Conditions Assessment
S5.C.1.d.i Phase II Permit requirement:
Permittees shall document and assess existing information related to their local receiving waters
and contributing area conditions to identify which receiving waters are most likely to benefit
from stormwater management planning.
By March 31, 2022, Permittees shall submit a watershed inventory and include a brief description
of the relative conditions of the receiving waters and the contributing areas. The watershed
inventory shall be submitted as a table with each receiving water name, its total watershed area,
the percent of the total watershed area that is in the Permittee’s jurisdiction, and the findings of
the stormwater management influence assessment for each basin. Indicate which receiving
waters will be included in the S5.C.1.d.ii prioritization process. Attach a map of the delineated
basins with references to the watershed inventory table.
This assessment helps jurisdictions gain an understanding of their receiving waters, the relative impacts
of urbanization and land use activities on those receiving waters, and what existing information is most
useful to guide their prioritization (S5.C.1.d.ii of the Phase II Permit).
Four steps are included in this overall assessment:
Step 1: Delineate basins and identify receiving waters,
Step 2: Assess receiving water conditions,
Step 3: Assess stormwater management influence, and
Step 4: Assess relative conditions, and contributions.
The outcome of the Receiving Water Conditions Assessment is a watershed inventory that identifies the
list of candidate basins and includes the information you need to support your prioritization process.
Although these steps are presented in consecutive order, they may be implemented concurrently if that
makes sense to the jurisdiction.
Step 1: Delineate Basins and Identify Receiving Waters
The first step in the Receiving Water Conditions Assessment is delineating the basins in your jurisdiction
and identifying all of your receiving waters. The appropriate scale for these basins ranges from about
one square mile (the smallest area likely to support a perennial stream) to up to about 20 square miles
total drainage area, including all contributing areas outside of your permit coverage area. Jurisdictions
may have compelling reasons to look at larger watersheds, but rivers and most large streams (more than
third Strahler order) are likely too large for SMAP actions alone to result in noticeable improvements in
the receiving waters.
Use the scale that best meets your end goal, i.e., whether the prioritization (S5.C.1.d.ii) is expected to be
driven by flow control or by toxics or nutrient loading reduction (or both). Counties may need to begin
at a larger scale to narrow the number of basins included in the Receiving Water Conditions Assessment.
Whatever the scale for the delineation, SMAP actions (S5.C.1.d.iii) will ultimately be identified for a
smaller catchment area or areas within the priority basin.
Stormwater Management Action Planning Guidance
Page 4
Publication No. 19-10-010
While it is not required to use GIS or other digital tools to complete this work, Ecology encourages
Permittees to use the “assessment units” from the Puget Sound Watershed Characterization Project as a
starting point (https://ecology.wa.gov/Water-Shorelines/Puget-Sound/Watershed-characterization-
project), or other existing GIS products. The Watershed Characterization’s “assessment units” provide a
first cut of basin delineations that may need to be refined to better reflect on-the-ground conditions
and/or meet the needs of this permit requirement. The Watershed Characterization Project may be able
to work with a jurisdiction to develop “assessment units” for some areas outside of the Puget Sound
Basin, if requested early and Ecology has the resources available. Permittees in Clark and Cowlitz
Counties may refer to the watershed delineation work that was done in developing the Lower Columbia
Region Monitoring Implementation Plan (Stillwater Sciences 2016).
To successfully complete this step, whether using the Watershed Characterization Project “assessment
units” or another existing source of information, or doing the work specifically for this process, you will
delineate all of the basin areas in your jurisdiction and identify the receiving water for each of those
basins. This exercise should rely on your MS4 map, which identifies your MS4 system, discharge
locations, and receiving waters.
1. Every part of your jurisdiction drains to a receiving water of some type and size. This step should
result in a map of your jurisdiction delineated into basins and a list of receiving waters to which
your MS4 discharges (small stream segments, wetlands, lakes, large rivers, Puget Sound) –
whether or not the receiving water is inside your jurisdictional boundaries.
2. Phase II Counties will do this step for your permit coverage area (Urbanized Areas and
designated Urban Growth Areas). You are encouraged to also consider additional areas in your
jurisdiction in order…

Western Washington Phase II Permit Appendix 3 Annual Report extract

Summary: WW Phase II Annual report questions for Cities, Towns and Counties stormwater planning extract

Western Washington Phase II Municipal
Stormwater Permit
Appendix 3 – Annual Report for Cities, Towns, and Counties – August 1, 2019
Page 1 of 9
APPENDIX 3 – Annual Report Questions for Cities, Towns, and
Counties
Permittees are required to submit the following information in an online annual report form, or an
alternative format provided by Ecology if requested, pursuant to Special Condition S9.A.
Reporting Requirements and SWMP
1. Attach a copy of any annexations, incorporations, or boundary changes resulting in an increase or
decrease in the Permittee’s geographic area of permit coverage during the reporting period per
S9.D.6.
2. Attach updated annual Stormwater Management Program Plan (SWMP Plan). (S5.A.2)
3. Implemented an ongoing program to gather, track, and maintain information per S5.A.3, including
costs or estimated costs of implementing the SWMP.
4. Coordinated among departments within the jurisdiction to eliminate barriers to permit compliance.
(S5.A.5.b)
4a. Attach a written description of internal coordination mechanisms. (S5.A.5.b)
Stormwater Planning
5. Have you convened an interdisciplinary team to inform and assist in the development, progress, and
influence of the stormwater planning program? (S5.C.1.a. – Required by August 1, 2020)
Coordination with long-range plan updates
6. List the relevant land use planning efforts that have taken place in your jurisdiction (land use plans
that are used to accommodate growth, stormwater management, or transportation). (S5.C.1.b.i(a)
and (b) – Required by March 31, 2021 & January 1, 2023)
7. List of stormwater capital projects (currently in or slated for future design and construction) that
resulted from this planning. (S5.C.1.b.i(a) and (b) – Required by March 31, 2021 & Jan 1, 2023)
8. Describe of watershed protection measures associated with stormwater management and land use
planning actions that resulted from this planning. (S5.C.1.b.i(a) and (b) – Required by March 31, 2021 &
January 1, 2023)
9. Were land acquisitions identified (or are planning ahead for) that are useful for stormwater facilities
to: accommodate growth or to better serve an existing developed area? (S5.C.1.b.i(a) and (b) –
Required by March 31, 2021 & January 1, 2023)
9a.If yes, for what purpose?
10. Identified corrective actions, in addition to the minimum requirements of the Municipal Stormwater
Permits to control or treat municipal stormwater discharges that pollute waters of the State (e.g.
Limits to impervious cover added to any zoning districts, regional facility planning, minimization of
vegetation loss, etc.)? (S5.C.1.b.i(a) and (b) – Required by March 31, 2021 & January 1, 2023)
Western Washington Phase II Municipal
Stormwater Permit
Appendix 3 – Annual Report for Cities, Towns, and Counties – August 1, 2019
Page 2 of 9
10a. If yes, briefly describe and list relevant plan or code sections, if applicable.
11. Updates to goals and policies related to investment in stormwater management facilities/BMPs?
(yes/no) (S5.C.1.b.i(a) and (b) – Required by March 31, 2021 & January 1, 2023)
11a. If yes, briefly describe.
12. Does the long-range plan identify the location and existing capacity of the stormwater facilities
owned or operated by the Permittee and show which of those stormwater facilities have unused
capacity? (S5.C.1.b.i(a) and (b) – Required by March 31, 2021 & January 1, 2023)
12a. Do these stormwater facility locations impact where housing, or other types of
development, are projected to be located or influence the acquisition of land? (If yes, how?)
12b. Does the long-range plan identify a lack of facilities and the potential impacts of
existing or new development to those areas and receiving waters?
12c. Any new proposed locations and capacities of stormwater facilities needed for the
timeframe of the plan?
13. Based on the projected population densities and distribution of growth over the planning period,
describe how stormwater runoff impacts are forecasted. Does stormwater management
information (including water quality) direct where growth is directed? (S5.C.1.b.i(a) and (b) –
Required by March 31, 2021 & January 1, 2023)
14. Did you submit a report as described in S5.C.1.b.i(b)? (Required no later than January 1, 2023)
Low impact development code-related requirements
15. Continue to design and implement local development-related codes, rules, standards, or other
enforceable documents to minimize impervious surfaces, native vegetation loss, and stormwater
runoff, where feasible? See S5.C.1.c.i. (Required annually)
16. From the assessment described in S5.C.1.c.i(a), did you identify any administrative or regulatory
barriers to implementation of LID Principles or LID BMPs? (Required annually)
16a. If yes, describe the barrier(s) and the measures taken to address them. (S5.C.1.c.i(a))
Stormwater Management Action Planning
17. Developed a watershed inventory as outlined in S5.C.1.d.i? (Submitted by
March 31, 2022)
17a. Attach watershed inventory as described in S5.C.1.d.i.
18. Developed a receiving water prioritization method and process as described in S.5.C.1.d.ii(a)-(c)?
(Required by June 30, 2022.)
18a. Attach receiving water priority ranking process as described in S.5.C.1.d.ii(a)-(c).
19. Developed a Stormwater Management Action Plan (SMAP) for at least one high priority area?
(S.5.C.1.d.iii – Required by March 31, 2023)
Western Washington Phase II Municipal
Stormwater Permit
Appendix 3 – Annual Report for Cities, Towns, and Counties – August 1, 2019
Page 3 of 9
19a. Attach SMAP(s).
Education and Outreach
20. Did you choose to adopt one or more elements of a regional program? (S5.C.2)
20a. If yes, list the elements, and the regional program.
21. Attach a description of general awareness efforts conducted, including your target audiences and
subject areas, per S5.C.2.a.i.
22. Conducted an evaluation of the effectiveness of the ongoing behavior change program and
documented recommendations as outlined in S.5.C.2.a.ii.(b). (Required no later than
July 1, 2020)
22a. If not, explain
23. Developed a behavior change campaign that is tailored to the community in accordance with
S5.C.2.a.ii.(c)? (Required no later than February 1, 2021)
23a. Attach the strategy and schedule developed in accordance with S5.C.2.a.ii.(c).
24. Began implementing strategy outlined in S.5.C.2.a.ii(c) (S5.C.2.a.ii.(d) – Required by April 1, 2021)
25. Attach the report developed in accordance with S5.C.2.a.ii.(e), which evaluated the changes in
understanding and adoption of targeted behaviors resulting from the implementation of the
strategy and any planned or recommended changes to the program in order to be more effective.
(Required no later March 31, 2024)
26. Promoted stewardship opportunities (or partnered with others) to encourage resident participation
in activities such as those described in S5.C.2.a.iii.
26a. Attach a list of stewardship opportunities promoted.
Public Involvement and Participation
27. Describe in Comments field the opportunities created for the public, including overburdened
communities, to participate in the decision-making processes involving the development,
implementation, and updates of the Permittee’s SWMP and the SMAP. (S5.C.3.a)
28. Posted the updated SWMP Plan and latest annual report on your website no later than
May 31 of each year?. (S5.C.3.b)
28a. List the website address in Comments field.
MS4 Mapping and Documentation
29. Maintained a map of the MS4 including the requirements listed in S5.C.4.a.i-vii?
30. Started mapping outfall size and material in accordance with S5.C.4.b.i? (Required no later than
January 1, 2020)
30a. Attach a spreadsheet that lists the known outfalls’ size and material(s).