Sammamish, WA Environmental Rules: Stormwater Management (2026)
Key Facts
- ESC requirement
- Applies even without a permit, SMC 16.15.090(1)
- Drainage manual
- King County Surface Water Design Manual
- Adopting section
- SMC 21.03.050, Chapter 9.04 KCC
- Repair window after violation notice
- 24 hours
- Max environmental penalty
- $25,000 plus restoration cost
Summary
Sammamish requires erosion and sediment control on any land-disturbing activity, whether or not it needs a clearing and grading permit, and separately requires drainage review under the King County Surface Water Design Manual, with a points-based penalty matrix for surface water violations.
16.15.090 Operating conditions and standards of performance. (1) Any activity that will clear, grade, or otherwise disturb the site, whether requiring a clearing or grading permit or not, shall provide erosion and sediment control (ESC) that prevents, to the maximum extent possible, the transport of sediment from the site to drainage facilities, water resources, and adjacent properties. Erosion and sediment controls shall be applied as specified by the temporary ESC measures and performance criteria and implementation requirements in the City's erosion and sediment control standards.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through Ordinance O2026-598, and legislation passed through August 18, 2026).
Full Breakdown
090(1) states that any activity that will clear, grade or otherwise disturb a site, permitted or not, must provide erosion and sediment control (ESC) that prevents sediment transport off-site to the maximum extent possible, following the City's adopted temporary ESC measures and performance criteria. 120(4) adds that clearing and grading is only allowed if the applicant shows silt-laden runoff exceeding City stormwater standards will be prevented, through a mix of site conditions, activity limits, and erosion/sedimentation control measures approved in writing by the Director; failing to maintain the approved erosion plan triggers a notice of violation, and if not repaired within 24 hours, a stop-work notice and order.
050, and if so, drainage plans consistent with the King County Surface Water Design Manual. 050 violations, including illicit discharges and connections into the municipal storm drain system, scored through a points matrix covering public health risk, environmental damage, and whether the discharge reached the municipal separate storm sewer system.
Violations & Fines
Each act or omission violating SDC 21.03.050 is a separate violation, and anyone who aids or abets a violation is treated as having committed it, per SMC 23.100.030. Financial penalties are set using a points matrix scoring public health risk, environmental damage and storm-sewer impact; general environmental damage/critical areas violations under SMC 23.100.010 can reach up to $25,000 plus the cost of restoration.
Frequently Asked Questions
Do I need erosion control even without a grading permit in Sammamish?
What drainage manual does Sammamish use for stormwater review?
What happens if I don't fix an erosion control problem after a notice of violation?
Sources & Official References
Other rules in Sammamish
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Stormwater Management in Nearby Cities
How other cities in King County handle stormwater management.