Permits and Permittees
Municipal Stormwater General Permits
- The Phase I permit regulates discharges from municipal separate
storm sewers owned or operated by Clark, King, Pierce and Snohomish
Counties; and the cities of Seattle and Tacoma.
- The Phase II Municipal Stormwater Permit rule extends the coverage
of the National Pollutant Discharge Elimination System (NPDES)
program to certain "small" municipal separate stormwater sewer
systems (MS4s). The Department of Ecology used
maps of the census
urbanized areas and jurisdictional boundaries
to identify Phase II jurisdictions. Ecology issued two Phase II
permits: one for Eastern Washington and one for Western Washington.
1990-1999: MS4 Permit Program Begins
- 1995 - Phase I Municipal Stormwater Permits Issued
first Washington State Municipal Stormwater Permits were issued on July 5, 1995
and became effective August 4, 1995. Three permits were issued for Phase I permittees
in the following water quality management areas:
Island/Snohomish (WRIAs 5 and 6), South Puget Sound (WRIAs 10, 11, and 12), and Cedar/Green (WRIAs 8 and 9).
Phase I of the EPA NPDES MS4 program for the history of the federal program.
- 1999 - Phase I Permit Issued to Clark County
In 1995 it became clear that Clark County triggered the 100,000 population threshold that
requires coverage under the Phase I MS4 permit. After several years of permit coverage application
and discussion with Ecology, a
permit was issued to Clark County on July 16, 1999.
- 1999 - Phase II of EPA's Stormwater NPDES
In 1999 the EPA issued the Small MS4 Stormwater Program rules, more commonly known as
Phase II of the NPDES Municipal Stormwater Permits. This
updated added a large number of new potential permittees, including operators of
medium and small sized MS4s in urbanized areas. Ecology began a stakeholder process to
educate and collaborate with likely WA State Phase II permittees.
2000-2010: Refinement and Expansion
- 2003 - Municipal Stormwater Working Groups
At the direction of the 2003 Legislature (HB 1689 - not adopted), Ecology
convened two panels to advise the agency on development of municipal stormwater
permits. Ecology incorporated those groups’ discussions into a
Report to the Legislature
- 2007 - Municipal Stormwater Permits Issued: Phase I and Phase II
The second set of Municipal Stormwater Permits was issued on January 17, 2007.
Phase 1 communities
(Snohomish, King, Pierce, and Clark Counties, and the cities of Seattle and Tacoma)
were no longer grouped by water quality management areas, and were rather issued separate coverages
under a general Phase I permit.
This cycle was also the first time coverage applied to numerous medium and small sized cities and
counties across the State of Washington. Two Phase II general permits were written, one for
and one for Eastern Washington,
to reflect the distinct hydrologic regimes of each.
Secondary permittees were also covered for the first time with this permit cycle, including the ports
of Seattle and Tacoma and numerous public facilities such as college campuses and prisons.
- 2007 - Permits Appealed
Thirteen parties appealed
the Phase I, Phase II Eastern Washington, and Phase II Western Washington
Municipal Stormwater Permits that Ecology issued in January, 2007. The parties to these appeals represented
cities, counties, and non-governmental organizations. Several parties also filed to intervene in the appeals.
- 2009 - Phase I and Phase II Modification
On June 17, 2009, Ecology
modified the 2007 municipal stormwater permits to
address the settlement agreements and the
Pollution Control Hearings Board (PCHB)
orders. More information on the appeals to the permit can be found on our
Appeals and Rulings webpage.
- 2010 - Phase I Modification
Ecology modified the Phase I Municipal
Stormwater permit on September 1, 2010.
The purpose of the permit modification was to incorporate Ecology's equivalency determination of
Clark County's Flow Control Mitigation Program. Ecology also incorporated minor updates to King County
and the City of Seattle's equivalency documents.
2011-Present: Continuing Refinement
- 2012 - Interim Permits Issued
At legislative direction (Senate Bill 6406), Ecology issued interim permits for
Phase II Western and Eastern Washington on August 1, 2012. Ecology also
reissued the Phase I permit on August 1, 2012. The Phase II permits
were reissued unmodified; the Phase I permit was reissued with minor modifications.
The effective dates for the Western permits were September 1, 2012 through July 31,
2013. The effective period for the Eastern permit was September 1, 2012 through
July 31, 2014, basically extending the Eastern permit by one year.
- 2012 - Five-Year Permits Issued
At the same time that it issued the three interim permits (above), Ecology issued
three five-year permits, effective August 1, 2013 for Phase I and Phase II Western
Washington, and effective August 1, 2014 for Phase II Eastern Washington.
- 2012 - Permit Appeal
During the appeal period for the reissuance of the five year Western Washington permits,
from August 1, 2012 to August 31, 2012, Ecology received the
of the Phase I and Western Washington Phase II permits on a variety of issues.
- 2014 - Western Washington Modification
The various issues raised by the appeals in 2012, as well as errata,
are resolved in the modification to the Western Washington permit modification
completed in 2014.
- 2016 - Phase I Modification
On July 20, 2016 Ecology modified the Phase I Municipal Stormwater Permit to incorporate, in Appendix 10 of the permit, the stormwater programs that Phase I municipalities adopted to provide equal or similar protection of receiving waters and pollutant control as compared to Appendix 1 of the permit. The proposed modification also includes a new appendix, Appendix 13, which describes adaptive management plan requirements for pollutants that discharge from the City of Seattle’s municipal separate storm sewer system outfalls to the Lower Duwamish Waterway.
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