California Code, Health and Safety Code - HSC § 40731

(a) Operations that create fugitive dust emissions, including, but not limited to, discing, tilling, material handling and storage, and travel on unpaved roads.

(b) Confined animal facilities, including, but not limited to, any structure, building, installation, barn, corral, coop, feed storage area, or milking parlor, including, but not limited to, a system for the collection, storage, treatment, and distribution of liquid or solid manure from domestic animals, including, but not limited to, cattle, calves, horses, sheep, goats, swine, rabbits, chickens, turkeys, or ducks, if those animals are corralled, penned, or otherwise caused to remain in restricted areas for commercial agricultural purposes, and feeding is by means other than grazing.

(c) Internal combustion engines used in the production of crops or the raising of animals or fowl, except an engine that is used to propel an implement of husbandry, as that term is defined in Section 36000 of the Vehicle Code, as that section existed on January 1, 2003.

(d) Other equipment, operations, or activities associated with the growing of crops or the raising of fowl or animals, that emit, or cause to be emitted, any regulated air pollutant, or any precursor to any regulated air pollutant.