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🌍 Environmental Rules/Erosion Control

Kirkland vs Seattle

How do erosion control rules compare between Kirkland, WA and Seattle, WA?

Kirkland and Seattle have similar restriction levels.

Kirkland, WA

King County

Heavy Restrictions

Kirkland requires temporary erosion and sediment control (TESC) plans for clearing and grading per KMC Chapter 115 and the Ecology stormwater manual, with wet-season rules limiting soil disturbance from October to April.

View full Kirkland rules →

Seattle, WA

King County

Heavy Restrictions

Seattle requires erosion and sediment control measures for all grading and land-disturbing activities under SMC Title 22, with mandatory best management practices to prevent soil runoff into waterways and Puget Sound.

View full Seattle rules →

Key Facts Comparison

FactKirklandSeattle
CodeKMC 115 + Ecology Manual-
TESC Threshold7,000 sq ft typical-
Wet SeasonOct 1 to Apr 30-
StabilizationRequired after grading pause-
DischargeMuddy water prohibited-
Plan Required-TESC plan required for all grading and land-disturbing permits
Stabilization Deadline-Exposed soil must be stabilized within 7 days of inactivity
Steep Slope Trigger-Additional protections on slopes of 40% grade or steeper
Enforcement-SDCI inspectors conduct site visits throughout construction

Highlighted rows indicate differences between cities.

Kirkland FAQ

Do I need a TESC plan for a small landscaping project?

Most small residential landscape projects fall below thresholds, but any work on steep slopes, near streams, or over 7,000 square feet generally requires a TESC plan.

Can I continue excavation in November?

Wet-season rules reduce the allowable exposed area and add stabilization deadlines. Projects must plan for rapid covers, mats, or seeding between grading phases.

Seattle FAQ

What erosion control measures are required during construction?

At minimum, sites must have silt fences along downslope perimeters, stabilized construction entrances to prevent tracking sediment onto streets, protection of all storm drain inlets, and dust control measures. The specific requirements depend on the project scope, soil type, and proximity to waterways or steep slopes.

Are there extra rules for construction on hillsides?

Yes. Projects on steep slopes (40 percent grade or steeper) trigger Seattle's Environmentally Critical Areas regulations, which require geotechnical studies, enhanced erosion control plans, and may restrict the extent of grading and vegetation removal allowed.

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