Western Washington Phase II Municipal Stormwater Permit Overview – 2024 to 2029
The timeline below provides an overview of major program deadlines for implementing permit requirements of S5 Stormwater Management Program
(SWMP) and S8 Monitoring and Assessment for Continuing City, Town, and County Permittees (By Date means “no later than…”). This is guidance only.
Table paraphrases requirements and does not include all ongoing program elements. Please see the permit for additional details and related
requirements.
S5 Permit
Components
Ongoing
Program
Implementation
2024
2025
2026
2027
2028
2029
A. Stormwater
Management
Plan
Annually update
& submit the
SWMP with
Annual Report
(S9)
– A.3.a. Cost
tracking: track
the cost of
development and
implementation
of each
component of
the SWMP
– A.3.b. activity
tracking: track #
of inspections,
follow up
actions, official
enforcement,
public ed
activities
By March 31
(ongoing from
this year
forward):
Submit the
(estimated) cost
of development
and
implementation
of each
component of
the SWMP and
sources of
funding.
S5 Permit
Components
Ongoing
Program
Implementation
2024
2025
2026
2027
2028
2029
A.5
Coordination
Ongoing
coordination
By March 31:
Submit
description of
internal
coordination
mechanisms
among
departments.
C.1
Stormwater
Planning
Ongoing
-Continue to
convene
interdisciplinary
team
-Assess and
report LID code-
related
requirements.
March 31:
Respond to
series of Annual
Report (AR)
questions for
coordination of
long-range plans
during this
permit term
Submit
completed
SMAP for new
catchment area,
or additional
actions for
existing SMAP.
By Dec 31:
Adopt and
implement tree
canopy
goals/policies to
support
stormwater
management.
S5 Permit
Components
Ongoing
Program
Implementation
2024
2025
2026
2027
2028
2029
C2. Public
Education &
Outreach
Ongoing:
Implementation
of ed & o
outreach
programs and
stewardship
By July 1:
Follow Social
Marketing
methodology to
develop strategy
and schedule
for new or
modified
campaign.
By Sept 1:
Begin to
implement
strategy
By March 31:
Submit report
on evaluation of
behavior change
campaign.
C3. Public
Participation
Ongoing:
-Create
opportunities for
public, including
overburdened
communities,
and specifically,
highly impacted
communities, to
participate in
SWMP and SMAP.
-Post SWMP and
Annual Report to
website by May
31.
By Dec 31:
Document
methods used
to identify
overburdened
communities
S5 Permit
Components
Ongoing
Program
Implementation
2024
2025
2026
2027
2028
2029
C4. Mapping &
Documentation
Ongoing
Maintain
mapping data
By March 31:
Submit
locations of all
known outfalls
according to
standardized
template in
annual report.
By Dec 31:
Use available,
existing data to
map tree
canopy to
support
stormwater
management on
Permittee-
owned or
operated
properties.
By March 31:
Map and assess
acreage of MS4
tributary basins
to outfalls or
discharge pts
with publicly
owned SW
Treatment or FC
BMPs/facilities.
Submit with the
Annual Report a
map(s) (.pdf)
and table (.xlsx)
with a
breakdown of
the MS4
tributary basins
(see permit for
details).
By Dec 31:
Map
overburdened
communities in
relation to
stormwater
treatment and
flow control
BMPs/facilities,
outfalls,
discharge
points, and tree
canopy on
Permittee-
owned/operated
properties.
S5 Permit
Components
Ongoing
Program
Implementation
2024
2025
2026
2027
2028
2029
C5. IDDE
Ongoing
– Implement
program to
prohibit, address,
and eliminate
illicit discharges.
– Train staff
– Field screen on
average 12% of
the MS4 each
year.
-Track and
maintain records
through WQ
WebIDDE or
submit .xml
following the App
12 schema.
By Dec 31:
Coordinate with
firefighting
agencies to be
notified when
PFAS-containing
AFFFs are used
during
emergency
firefighting
activities.
By Jan 1:
Update and
implement
procedures to
minimize
discharges to
MS4 during
firefighting post-
emergency
cleanup and
disposal
activities.
By July 1:
Update
ordinance or
other regulatory
mechanism in
effect, if
necessary, to
meet the
requirements of
this section.
C6. Controlling
Runoff
Ongoing:
– Implement &
enforce program
to reduce
pollutants in
runoff.
– Train Staff
By June 30:
Adopt and make
effective local
program that
meets
requirements of
S5.C.6.b.i-iv.
S5 Permit
Components
Ongoing
Program
Implementation
2024
2025
2026
2027
2028
2029
C7. Stormwater
Management
for Existing
Development
(SMED)
March 31:
Provide list of
planned,
individual
projects
scheduled for
funding or
implementation
during this permit
term for the
purposes of
meeting the
assigned
equivalent
acreage in
Appendix 12
using the using
the report format
in Appendix 12.
By March 31:
Submit
documentation/
report showing
that the
jurisdiction has
fully funded,
started
construction or
completely
implemented
project(s) that
meet assigned
equivalent
acreage as
described in
App 12.
Report the
amount of
estimated or
projected
equivalent acres
managed by
facility retrofits
which will be
credited to the
next permit term
(2029-2034)
S5 Permit
Components
Ongoing
Program
Implementation
2024
2025
2026
2027
2028
2029
C8. Source
Control for
Existing
Development
Ongoing:
– Implement &
enforce program
to reduce
pollutants in
runoff from
existing
development.
-Update
inventory at least
once per 5 years.
-Annually inspect
20% of inventory
list.
– Train Staff
Aug 1:
Update and
make effective
the ordinance or
other
enforceable
document, if
necessary, to
meet the
requirements of
this section.
S5 Permit
Components
Ongoing
Program
Implementation
2024
2025
2026
2027
2028
2029
C9. Operations
& Maintenance
Ongoing:
-Inspect and
maintain
Permittee
owned/operated
catch basins and
stormwater
BMPs/facilities,
and regulated
stormwater
BMPs/facilities.
-Maintain
updated SWPPP
at heavy
equipment,
maintenance,
and storage
facilities.
-Train Staff
Dec 31:
All catch basins
and inlets
owned or
operated by the
Permittee shall
be inspected,
and every two
years thereafter.
By June 30:
Adopt updates
to maintenance
standards, as
needed, to meet
the
requirements of
this section.
July 1:
Develop and
implement
street sweeping
program.
Between July –
Dec:
Sweep high
priority areas
once
By Dec 31:
Update
documentation
of practices,
policies, and
procedures to
reduce SW
impacts from all
permittee lands
By March 31
(ongoing from
this year
forward):
Report on all
items described
in S5.C.9.e.v(a-
f).
Between July-
Sept (ongoing
from this year
forward):
Sweep high
priority areas
once
Annually
(ongoing from
this year
forward):
Sweep high
priority areas 2
additional times
to the July-Sept
event at timing
determine by
Permittee.
S8 Permit
Components
Ongoing
Program
Implementation
2024
2025
2026
2027
2028
2029
S8.A & S8.B
By Aug 15, 2025-
2029:
Make annual
payments into
SAM per S8.D
instructions
By Dec 1: All
Permittees who
chose S8.A.2
and/or S8.B.2
option for the
2019-2024
permit make a
one-time
payment to
SAM fund per
S8.D.
All Permittees,
except
Aberdeen and
Centralia, shall
notify Ecology
in writing,
certified with a
G19 signature,
if they will
select S8.A.2.a
or S8.A.2.a for
Regional Status
and Trends
Monitoring, as
well as their
choice of
S8.B.2.a or
S8.B.2.b for
SWMP
Effectiveness
and Source ID
Studies.
S8 Permit
Components
Ongoing
Program
Implementation
2024
2025
2026
2027
2028
2029
S8.C –
Stormwater
Discharge
Monitoring
(applies only to
Permittees who
choose to
conduct
discharge
monitoring per
S8.A.2.b and/or
S8.B.2.b.
By June 30:
Submit a draft
stormwater
discharge
monitoring
QAPP for review
and approval.
By August 15:
Final QAPP
submitted to
Ecology, or
within 60 days of
receiving
Ecology's
comments on
the draft
(whichever is
later).
By Oct 1:
Flow monitoring
shall begin, or
within 30 days of
receiving
Ecology’s final
QAPP approval
(whichever is
later).
By Oct 1:
Stormwater
discharge
monitoring fully
implemented.