Erosion Control: Redmond vs Seattle
How do erosion control rules compare between Redmond, WA and Seattle, WA?
Redmond and Seattle have similar restriction levels.
Redmond, WA
King County
Redmond requires construction-phase erosion and sediment control BMPs on any ground disturbance over 2,000 sf under RMC Title 15 and the DOE Stormwater Manual, with daily inspection during wet season.
View full Redmond rules →Seattle, WA
King County
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
| Fact | Redmond | Seattle |
|---|---|---|
| Trigger | 2,000 sf disturbance | - |
| SWPPP | Required with permit | - |
| Wet season | Oct 1 to Apr 30 | - |
| State permit | 1 acre triggers CSWGP | - |
| 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.
Redmond FAQ
Do I need silt fence for a small Redmond addition?
For most ground disturbance over 2,000 sf, yes, along with other erosion BMPs during the entire project.
Can I keep bare soil exposed over winter?
No, during the Oct 1 to Apr 30 wet season disturbed soils must be stabilized with mulch, cover, or grass.
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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