Aliso Viejo, CA Environmental Rules: Erosion Control (2026)

The City of Aliso Viejo, in Orange County, California, regulates construction erosion in Article XIII of its Grading and Excavation Code, Chapter 13.08, and the building official administers it. The rainy season runs from October 1st to April 30th. During that window, temporary or permanent devices such as desilting basins, check dams and riprap must be used where necessary, and no grading above 200 cubic yards on a single permitted site is allowed unless an erosion control system has been approved or waived.

Several operating rules sit beside the seasonal cutoff. Paved streets and sidewalks must be kept free of loose soil, construction debris and trash, with street sweeping or an equally effective method used on a regular basis. Watering is not allowed for street cleaning except for fine material, unless the water is vacuumed up. Unless the building official approves otherwise, the owner must retain a civil engineer to design all erosion and sediment control improvements and to give initial approval of installation during each rainy season until final approval of the grading permit. Desilting facilities are required at drainage outlets, and compacted earth basins must reach a relative compaction of 90 percent of maximum density, backed by a soil engineering report. Slopes more than five feet high need effective planting, and slopes over 15 feet high can require irrigation. Removable protective devices must be in place at the end of each working day when the five-day rain probability forecast exceeds 40 percent.

Paperwork follows a calendar. Under § 13.08.340, erosion control plans for projects under grading permit go to the building official for approval by September 15th each year. For a single residential lot, the plan can be waived if an approved system is in place before October 15th. Under § 13.08.350, silt and debris must be removed from devices after each rainstorm. If the contractor, permittee or owner fails to maintain them, the building official can order emergency work at the owner's cost, revoke the grading permit in writing, and hold renewal until a system is installed and a fee of one-half the amount of the original grading permit is paid. Section 13.08.330(P) also makes a violation of a federal or state stormwater permit, or of AVMC 7.35.010 et seq., a violation of the chapter. Under § 13.08.430, all erosion control measures must be complete before final approval of the grading permit.