Stormwater manuals
Our stormwater manuals provide stormwater permit implementation and management guidance. Contact your municipality or permit administrator to determine which manual you need and for questions regarding implementation of stormwater management guidance.
Ecology's Stormwater Management Manuals (SWMMs)
The dropdowns below provide access to past and present SWMMs.
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Emerging guidance
Stormwater management is evolving. As such, stormwater management guidance documents are often published in between versions of Ecology’s SWMMs. Stormwater management guidance documents released after publication of the latest SWMMs are provided in the “Additional Resources” folder within the interactive online version of the SWMMs. Direct links are provided below:
- Emerging Guidance in the 2024 Stormwater Management Manual for Western Washington (SWMMWW)
- Emerging Guidance in the 2024 Stormwater Management Manual for Eastern Washington (SWMMEW)
Equivalent regional stormwater manuals
In some cases, municipal stormwater permittees have the option of either adopting portions of the appropriate Ecology Stormwater Manual or portions of a regional manual determined to be equivalent to the Ecology Stormwater Manual. For more information, visit the equivalent stormwater manuals for municipal stormwater permits webpage.
Related links
Contact information
Amanda Heye, P.E.
SWMMQuestions@ecy.wa.gov
360-870-5283