Authorities announced the results of the bust at a Wednesday press conference, adding that it was only a fraction of the illicit marijuana grows in the area.
The problem is wide-ranging in the Antelope Valley, officials said, and has grown tremendously during the coronavirus pandemic. Armed cartel members run massive illegal grows, some spanning dozens of greenhouses, that are detrimental to the state's legal marijuana market.
Multiple law enforcement agencies carried out a 10-day operation in the Antelope Valley last month that resulted in 131 arrests and the seizure of more than 33,000 pounds of harvested marijuana plants.
Yet the undertaking only demolished 205 illegal grows out of the 500 seen by aerial surveillance in the area. Last year, Sheriff Alex Villanueva said only 150 illegal grows were identified in the Antelope Valley. Scores more exist in other nearby counties.
Authorities said drug cartels have been stealing millions of gallons of water a day to feed illegal marijuana grows in the Antelope Valley.
Asked where the water was being stolen from, Rep. Mike Garcia, who represents the state's 25th District, said: "Right here from our local aqueduct system. The California Aqueduct flows right through the Antelope Valley. They're taking it out of wells. They're stealing it from fire hydrants."
Villanueva said the cartels are "stealing water in the middle of the night from the farmers."
Villanueva said the stolen water is typically loaded onto tanker trucks and then delivered to the grow sites in the area.
California broadly legalized recreational marijuana sales in January 2018. But the black market is thriving, in part because hefty legal marijuana taxes send consumers looking for better deals.
Officials sought to differentiate between the Antelope Valley operation and the legal market.
"This is not a war on the legal cannabis business in California," Garcia said.
The Associated Press contributed to this report.