Grading & Drainage: Castaic vs Santa Monica
How do grading & drainage rules compare between Castaic, CA and Santa Monica, CA?
Castaic and Santa Monica have similar restriction levels.
Castaic, CA
Los Angeles County
Grading in unincorporated LA County requires permits from Building & Safety. The LA County Flood Control District manages the regional drainage system with 487 miles of channels and 2,919 miles of storm drain. Retaining walls over 4 ft require permits. Coastal areas have additional requirements for terracing and landscaping.
View full Castaic rules →Santa Monica, CA
Los Angeles County
Santa Monica requires adequate grading and drainage for all development. French drain systems with minimum 12x12 inch gravel cross-section required for downspout/gutter connections through curb face. The stormwater utility fee funds the drainage system.
View full Santa Monica rules →Key Facts Comparison
| Fact | Castaic | Santa Monica |
|---|---|---|
| Grading Permit | Required from Building & Safety | - |
| Flood Control | LACFCD manages regional system | - |
| Retaining Walls | Permit if over 4 ft | - |
| Coastal | Terracing and native landscaping | - |
| French Drain | - | 12x12 inch gravel minimum |
| Stormwater Fee | - | Based on parcel BMU |
| BMU | - | 0.0637 for avg single-family |
| Storage Areas | - | Must have adequate drainage |
Highlighted rows indicate differences between cities.
Castaic FAQ
Do I need a grading permit in unincorporated LA County?
Most grading work requires a permit from Building & Safety. Exemptions exist for less than 50 cubic yards on a single lot that doesn't obstruct drainage. Contact (626) 458-3171 to confirm.
Can I change the drainage on my property?
You cannot redirect concentrated runoff onto neighboring properties. All drainage must go to approved outlets. Significant drainage changes require a grading permit and may need engineering plans.
What reports are needed for hillside grading?
Hillside projects typically require a soils report, geology report, and geotechnical recommendations. The county may require additional studies for slopes, seismic hazards, or landslide-prone areas.
Santa Monica FAQ
Do I need a grading permit?
Generally required for earth-moving over 50 to 100 cubic yards or changes to existing drainage patterns. Small landscaping projects are usually exempt.
My neighbor changed their grading and water flows onto my property. What can I do?
Contact Santa Monica code enforcement. Redirecting drainage onto neighboring properties violates most municipal codes. The neighbor may be required to restore proper drainage.
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