Cal. PUC § 740.9

(a) Any optional binding mandatory curtailment program adopted by the commission that exempts customers from Stage 3 rotating outages in exchange for partial load curtailments during every rotating outage period shall provide, for agricultural and water supplier customers, the use of backup generation to offset the curtailed load under the program, to the extent the use of backup generation is allowed under existing law, including, but not limited to, all relevant local air pollution control district and air quality management district rules and regulations.

(b) As used in this section, “agricultural customers” means any customer involved in the production of or processing of agricultural products. “Water suppliers” means those water agencies or suppliers as defined in Section 20200 of the Water Code and Section 241 of the Public Utilities Code.