Tustin, CA Environmental Rules: Erosion Control (2026)

Tustin City Code Chapter 9 of Article 8 governs grading, and Section 8923 sets the City's erosion control and water quality requirements. Cut and fill slopes and the project site must be prepared and maintained against erosion, generally through effective planting installed as soon as practical and before final approval; drought-resistant and, in hillside areas, fire-retardant plants are recommended. No grading over 200 cubic yards may proceed on any single permitted site between October 15 and April 15 unless an erosion control system has been filed and approved, or waived in writing, by the Building Official.

Unless waived, the owner must retain a civil engineer to inspect and give initial approval of permanent and semi-permanent erosion and sediment control devices every rainy season (October 1 through April 30, per the Section 8905 definitions) and to revise the plan as field conditions require. Desilting facilities are required at every drainage outlet from a graded site, and desilting basins built of compacted earth must reach 90 percent relative compaction, verified by a soil engineering report submitted to the Building Official. During the rainy season, disturbed areas that are not actively being graded must be fully protected with best management practices, and standby erosion-control materials must be stored on site and ready to deploy within 48 hours of a forecast with a 50 percent chance of rain, even in the dry season.

Removable protective devices must be in place at the end of each working day whenever the five-day rain forecast exceeds a 40 percent chance, and slopes over five feet high need effective planting, with slopes over 15 feet potentially requiring irrigation.