Grading & Drainage: Altadena vs Carson
How do grading & drainage rules compare between Altadena, CA and Carson, CA?
Carson has fewer restrictions than Altadena.
Altadena, CA
Los Angeles County
Hillside grading exceeding 2,500 cubic yards cut + fill requires a Conditional Use Permit in Altadena (CSD 22.306.060.B.2.b). Grading during the Oct 15 – Apr 15 rainy season is subject to Public Works erosion-control requirements.
View full Altadena rules →Carson, CA
Los Angeles County
Carson enforces grading and drainage standards by adopting the California Building Code (Title 24 Part 2) including Appendix J — Grading. A grading permit is required for fill or excavation exceeding the thresholds in CBC Appendix J §J103 (generally >50 cubic yards or cuts/fills more than a few feet deep). Drainage must be conveyed by approved storm drains or graded swales, must not cross sidewalks or driveways (except single-family driveways), and must not be diverted onto adjacent properties.
View full Carson rules →Key Facts Comparison
| Fact | Altadena | Carson |
|---|---|---|
| Code Section | Altadena CSD 22.306.060.B + LA County 22.140.240 | - |
| CUP Threshold | 2,500 cy cut + fill | - |
| Haul Route | Required ≥1,000 cy off-site | - |
| Rainy Season | Oct 15 – Apr 15 (extra controls) | - |
| Local citation | - | Carson Building Code (CMC Art. 8) adopting CBC Appendix J — Grading |
| Grading permit threshold | - | Generally >50 cubic yards excavation or fill (CBC Appendix J §J103) |
| Foundation drainage | - | Minimum 5% slope away from foundation for first 10 feet (CBC Appendix J §J109) |
| Slope ratios | - | Fill slopes ≤2:1 H:V; cut slopes per soils report |
| Stormwater connection | - | Drainage must connect to city-approved storm drain (CMC Art. 4 Ch. 8) |
Highlighted rows indicate differences between cities.
Altadena FAQ
Do I need a permit to grade my Altadena hillside lot?
Yes — a Minor Conditional Use Permit is required for any hillside development, and a full CUP if grading exceeds 2,500 cubic yards total (CSD 22.306.060.B).
Carson FAQ
Do I need a permit to regrade my Carson backyard?
Minor residential regrading involving less than 50 cubic yards of earth movement and not altering drainage patterns is typically exempt under CBC Appendix J §J103, but any work that changes how water flows on or off your lot — particularly toward a neighbor — requires a grading permit and engineered drainage plan.
Can I direct downspout water to my neighbor's yard?
No. Both CBC Appendix J §J109 and California common-law nuisance prohibit diverting concentrated drainage onto adjacent property. Downspouts must discharge onto your own property, into approved on-site retention, or via a drain connected to the public storm drain.
What is the minimum lot grading slope?
Around buildings, finished grade must slope away from foundations at a minimum 5% (6 inches over the first 10 feet) per CBC Appendix J §J109. Swales conveying lot drainage must have a minimum 2% slope to an approved point of discharge.
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