According to the City's MS4 permit issued by the San Diego Regional Water Quality Control Board, Irrigation water runoff from landscapes and other green areas to storm drain systems, creeks, and wetland is considered illicit discharge and is illegal.
Water Efficient Landscaping Regulations
The purpose of the City's Water Efficient Landscaping Regulations and Guidelines (WELO) is to promote the design, installation, and maintenance of landscaping in a manner that conserves regional water resources by ensuring that landscaping projects are not unduly water-needy and that irrigation systems are appropriately designed and installed to minimize water waste.
By following the WELO guidelines it is expected that less water is wasted and at the same time runoff from irrigation to the storm drain system is minimized or eliminated. In some cases, even the most perfect design is not enough to ensure that there will be no illegal discharge of irrigation water to storm drain systems, therefore, constant inspection and maintenance of landscape irrigation system is key to the goal of zero over-irrigation runoff.