Los Angeles, California - California law enforcement agents have seized more than one million illegally grown marijuana plants this year. It is an attempt to curb illicit cultivation of the cash crop that continues to undercut the state's struggling legal market for pot, authorities said Monday.

California Attorney General Rob Bonta said Monday that agents assigned to the state's Campaign Against Marijuana Planting, or CAMP, program destroyed about 1.2 million plants discovered at unlicensed grow sites and seized 180,000 pounds of processed marijuana.

The crackdown took place over an unspecified 13-week period in 26 counties.

Agents also confiscated 165 firearms and collected 67,000 pounds of equipment, such as dams and water lines that are used to divert water from public sources to irrigate plants, Bonta said. The siphoning of water by illegal pot farmers has increasingly become a concern amid California's worsening drought.

The attorney general also said that insecticides banned in the state were found at grow sites, some of them so toxic that they kill wildlife and poison groundwater and public waterways.

Bonta said the California Department of Justice planned to conduct a six-month review of the CAMP program, which has existed since 1983, to gauge whether it was addressing what he called the "environmental, the labor and the economic impacts" of illegal cannabis cultivation.

Illegal grows have at times exploited laborers, Bonta said, forcing them to work in unsafe conditions. They also have wreaked havoc on legal grow operations, which struggle to compete with black market operators unencumbered by the taxes, permits, and fees required under California's marijuana laws.

Bonta said the state has a duty to support its legal cannabis market.

"We want that market," he said, "for more and more to enter — to leave the illicit marketplace and enter the legal marketplace." State authorities plan to encourage that transition "with carrots and sticks," he said.

Karen Mouritsen, director of the US Bureau of Land Management in California, said agents this year also seized and destroyed 169,000 illegal marijuana plants raised at 80 sites on federal land in the state.