Building Cities in the
Rain
Watershed Prioritization for
Stormwater Retrofits
PUBLICATION SUMMARY
Title: Building Cities in the Rain
Publication Number: 006
Month Year Published: September 2016
Online/Print Availability: Yes/No
Short Description: This guidebook presents recommended data and a
process for prioritizing watersheds for
stormwater retrofit investments.
Project Leads: Heather Ballash, AICP
Author: Heather Ballash, AICP
Contributing Writers/Editors: The Building Cities in the Rain Work Group
Number of Pages 49
Key Words Stormwater Infrastructure, Watershed Planning
ACKNOWLEDGEMENTS
Washington Department of Commerce:
Brian Bonlender, Director
Local Government Division:
Mark Barkley, Assistant Director
Growth Management Services Unit:
Dave Anderson, AICP
Interim Managing Director
This project has been funded wholly or in part by the United
States Environmental Protection Agency under Puget Sound
Ecosystem Restoration and Protection Cooperative Agreement
Grant PC-00J20101 with Washington Department of Ecology.
The contents of this document do not necessarily reflect the
views and policies of the Environmental Protection Agency,
nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
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Table of Contents
Executive Summary: Building Cities in the Rain……………………………………………………………..1
Chapter 1: Introduction………………………………………………………………………………………………….5
1.1: Purpose of this Watershed Prioritization Guidance…………………………………………..5
1.2: Why Prioritize Watersheds for Stormwater Retrofits?……………………………………6
1.3: The Redmond Experience………………………………………………………………………………….7
1.4: Background of the Building Cities in the Rain Project………………………………………..7
Chapter 2: Phasing of Prioritization Guidance – Focus on Regional Growth Centers…….10
Chapter 3: Multiple Community and Regulatory Benefits………………………………………..…..11
3.1: Clean Water Act………..…………………………………………………………………………………….11
3.1.1: NPDES Municipal Permits………………………………………………………………….…..11
3.1.2: Prioritization of Receiving Waterbodies for Stormwater Retrofits…………12
3.1.3: Watershed Management Planning for Stormwater Control Transfers.…..13
3.1.4: Stormwater Control Transfer Programs…………………………………………………13
3.2: Growth Management Act – Helping Communities Plan Strategically for Their
Future………………………………………………………………………….………………………………….15
3.2.1: Capital Facilities and Utilities Plans…………………….…………………………………16
3.2.2: Creating Compact Communities in Regional Growth Centers……………….16
3.2.3: Transportation Demand Management and Infrastructure under
VISION 2040………………………………………….……………………………………….………17
3.2.4: Economic Development and Revitalization……………………………………………17
3.2.5 Subarea Plans and Environmental Review………………………………………………17
3.3: Puget Sound Action Agenda…..……………………………………………………………………..…18
3.4: Puget Sound Salmon Recovery Plan…………………………………………………………………18
3.5: Climate Change………………………………………………………………………………………………..19
3.6: Environmental Justice………………………………………………………………………………………20
Chapter 4: Prioritizing Watersheds for Stormwater Investment……………………………………21
4.1: Policy Framework/Prioritization Goals…………………………………………………………….22
4.2: Process and Data for Prioritization of Watersheds…………………………………………..22
4.3: Using Local Data………………………………………………………………………………………………24
Chapter 5: Local Data Sources for Prioritization of Watersheds……………………………………27
5.1: Working with the Tribes, Federal and State Agencies, and the Public……………..28
5.1.1: Seeking Input from the Tribes……………………………………………………………….28
5.1.2: Seeking Input from Natural Resource Agencies……………………………………..28
5.1.3: Involving the Public in Watershed Prioritization…………………………………….28
5.2: Seeking Approval from Ecology (Stormwater Control Transfer Programs)……….28
5.3: Next Steps……………………………………………………………………………………………………….28
5.4: Local Data for Prioritizing Flow Control, Low Impact Development and Runoff
Treatment……………………………………………………………………………………………………….29
Appendices
Appendix A: Definitions……………………………………………………………………………………………….39
Appendix B: Building Cities in the Rain Work Group Participants…………………………………41
Appendix C: Stormwater Control Transfer Programs……………………………………………………42
Appendix D: Regional Growth Centers and 40/20 Basins Near Flow Control Exempt
Waters, Map…………………………………………………………………………………………………………………44
Appendix E: Who’s Covered Under the Municipal Stormwater Permits………………………..45
Appendix F: Stormwater Retrofit Prioritization Process, Washington State Department of
Transportation NPDES and Sate Waste Discharge Municipal Stormwater
Permit………………………………………………………………………………………………………46
Appendix G: Other Resources……………………………………………………………………………………….48
Building Cities in the Rain
Executive Summary
Building Cities in the Rain
Targeted watershed recovery and urban redevelopment and revitalization go hand in
hand. This guidance describes an optional process for prioritizing watersheds for
stormwater retrofits1 and the recovery of aquatic habitat in urban areas. It is
intended to provide a tool for local governments to target investment in stormwater
retrofits in a way that leverages opportunities for salmonid habitat restoration and
facilitates redevelopment in urban centers.
Problem Statement
The impetus for this guidance is two-fold, originally based on the experience of two
cities. The City of Tacoma has experienced challenges with attracting redevelopment
to areas of the City planned to accommodate growth under the Washington State
Growth Management Act. The City observed that the complexity and cost of
redevelopment in highly urbanized areas is exacerbated by a number of factors,
including stormwater management requirements. Paired with a sluggish economy,
low rents, and high vacancy rates, these requirements have contributed to pushing
redevelopment projects out of Tacoma and into lower-density areas of the county.
The City sees this as contrary to the intent of the Growth Management Act to densify
these urban areas. The City believes there is a conflict between the requirements of
the Growth Management Act and the National Pollutant Discharge Elimination
System (NPDES).
Seeking to avoid site-by-site facilities that consume land designated as Regional
Growth Centers2, the City of Redmond built regional stormwater facilities to serve its
Downtown and Overlake Regional Growth Centers. The facilities have cost $70 million
to date, and more investment is required to equip both regional growth centers with
stormwater infrastructure. Although this accomplished the objective of avoiding site-
by-site facilities, the multimillion dollar investment will likely not generate healthy
aquatic habitat. In response to this reality, the City of Redmond stormwater utility
picked up an additional element of its comprehensive plan to implement: restoring
aquatic habitat in its urban watersheds. The City chose to develop a watershed
management plan that prioritizes watersheds for rehabilitation efforts that will
1 For purposes of this guidance document, the term “stormwater retrofit” or “retrofit” refers to an
improvement in stormwater management that treats stormwater runoff or controls stormwater flow
for an existing or redeveloped surface that was not previously receiving that level of runoff treatment
or flow control. A “redeveloped surface” means a surface that will require the same or more
stormwater runoff treatment or flow control to meet the NPDES Minimum Requirements. This
improvement in stormwater management can sometimes be transferred through an Ecology
approved plan. Some retrofits are installed as part of the structural stormwater controls obligations
under the Phase 1 NPDES Municipal Permit. See Appendix A, Definitions.
2 The Puget Sound Regional Council has designated 29 urban centers in central Puget Sound as
regional growth centers planned to accommodate housing (53 percent of residential growth) and
employment (71 percent of employment growth) by 2040.
Building Cities in the Rain
Executive Summary
support aquatic habitat for salmon. The Citywide Watershed Management Plan,
approved by Ecology, allows the City to transfer certain stormwater control
improvements from development sites and into areas that drain to water bodies
targeted for recovery.
The current rate and pattern of redevelopment of urban areas that will require
stormwater retrofits will be based on redevelopment market forces and not on the
highest-priority watersheds. The predicted annual rate of mitigation of new and
redevelopment in Puget Sound is 1.6 percent over a 30-year period3. At this rate, it
will take more than 60 years to fully retrofit all watersheds for stormwater
management in the Puget Sound region, and for any urbanized water body to be
healthy, in the Puget Sound region. Redevelopment will occur where the market
demands, and not necessarily in the watersheds with the highest potential for
environmental improvement or restoration.
There is not enough funding to construct stormwater facilities in areas developed
with impervious surface4 in all watersheds in the immediate future5. In order to
protect and restore uses (including salmon and shellfish recovery) in high-priority
waterbodies, some jurisdictions will not want to wait for redevelopment to occur in
the watersheds where those waterbodies are located. Prioritization of watersheds
for stormwater retrofits allows jurisdictions to leverage all available funds in
watersheds with the most opportunity for restoring healthy aquatic habitat.
Uses for Prioritization
The prioritization described in this report can currently provide environmental
benefits in a number of different contexts, such as:
ï‚· Informing elected officials and the general public of environmental assets in
their community, and the current condition of those assets.
ï‚· Informing the needs assessment for the Capital Facilities Element of a local
comprehensive plan, including the location and capacity of needed or
expanded facilities to adequately control stormwater runoff from existing
development;
ï‚· Targeting stormwater control investment under a structural stormwater
control program required under the Phase I permit, S5.C.6;
3 Analysis of Stormwater Mitigation Projected to be Constructed by 2040 as Part of New and
Redevelopment in WRIA 9, King County, 2014. Note: This number is based on many of the exemptions
under the municipal permit not being utilized.
4 For example, pavement and roofs.
5 The Stormwater Retrofit Analysis and Recommendations for Juanita Creek Basin in the Lake
Washington Watershed (2012) found that approximately 68 percent of the 6.8 square mile basin is
heavily developed with impervious surfaces (pavement, roofs, etc.). Estimated costs in 2011 dollars to
achieve the most effective mitigation were estimated to be $1.4 billion ($30 – $200 million a square
mile). However, it should be noted that Juanita Creek has high property values with locations of
facilities near waterfront. The cost to retrofit may be lower in other urban areas.
Building Cities in the Rain
Executive Summary
ï‚· Prioritizing project proposals for a grant from the Ecology Stormwater
Financial Assistance Program to address pollution caused by existing
development;
ï‚· Informing water clean-up plans (Total Maximum Daily Load); or
ï‚· Establishing a stormwater control transfer program that targets high-priority
watersheds for transfer of stormwater retrofits from watersheds where local
comprehensive plans encourage redevelopment and urban infill.6
This watershed prioritization guidance can be used on its own for prioritizing
receiving waterbodies for voluntary stormwater retrofit, or it can be used as
companion guidance to Ecology’s Stormwater Control Transfer Program: Out of the
Basin – Second Draft7 guidance as part of an infill or redevelopment strategy to
increase capacity in urban centers.
Anticipated Results
Prioritization allows a jurisdiction to target stormwater retrofit investments that
provide environmental benefits to areas with the most potential for restoration,
while also meeting the requirements of the Growth Management Act. Prioritization
can provide a tool for targeting the location of and investment in improved
stormwater controls, including regional detention facilities8. In one specific
application, it can support a stormwater control transfer program. A transfer
program is designed to provide an equivalent and more efficient approach to
stormwater management than the Washington Department of Ecology’s default
program allows.
Prioritization allows cities and counties to move away from the current approach of
developer-funded site-by-site stormwater facilities that consume land and that have
the potential to increase development costs in urban centers that are designated to
accommodate projected population and employment growth. Prioiritzation would
allow cities and counties to put their efforts into high-priority areas. Facilitating
redevelopment in urban centers already reduces the stormwater impacts of sprawl
and development in greenfields.
Prioritization of watersheds for stormwater retrofits can target those areas with the
most potential for reducing stormwater impacts and restoring salmon habitat. Salmon
recovery plans do not address the stormwater impacts from development that
degrade salmon habitat in urbanized areas. Building stormwater retrofits that
leverage habitat restoration projects also increase the likelihood that salmonids will
survive in urban water bodies.
6 See Appendix C, Stormwater Control Transfer Program, and Subsection 3.1.4 on page 13.
7 Ibid 6.
8 A regional detention facility is a stormwater quantity control structure designed to correct existing
surface water runoff problems of a basin or sub-basin. This term is also used when a detention facility
is sited to detain stormwater runoff from a number of new developments or areas within a catchment.
See Appendix A, Definitions.
Building Cities in the Rain
Executive Summary
Process and Data Sources for Watershed Prioritization
This guidance recommends a stepwise approach to prioritizing watersheds for
stormwater retrofits. Locally adopted policies regarding water quality and habitat
can provide the basis and framework for prioritization and the goals of a stormwater
control transfer program. Regional-scale data, such as the Puget Sound
Characterization project, and regional plans, such as Chinook Salmon Recovery,
Water Resource Inventory Area plans, will support a high-level analysis for local
prioritization. But the final screen must be informed by local, watershed-specific,
information. This guidance provides recommendations on types and sources of data
easily accessible to local governments for a prioritization process.
CHAPTER 1:
Introduction
1.1 Purpose of this Watershed…