More than 16,000 marijuana plants and enough poison to kill more than 750 black bears were found this week during eradication efforts in Humboldt County, officials announced Thursday.

”What they're finding is pretty astounding,” Humboldt County Sheriff Mike Downey said. “Growers are using vastly more than what would be needed. It's enough to kill armies of rodents.”

Humboldt County Sheriff's Office deputies, U.S. Forest Service agents, Hoopa Valley Tribal Police officers and the Cannabis Eradication and Reclamation Team investigated and eradicated multiple grow sites this week near Willow Creek, Hoopa Valley and Orleans, alongside three civilian researchers with backgrounds in wildlife, toxicology and ecology.

Officers removed 17 pounds of anticoagulant rodenticide bait from three sites, according to a sheriff's office press release. Researchers reported the amount of poison found could kill the equivalent of 2,753 wood rats, 14 Pacific fishers or five spotted owls.

At one site, deputies and researchers located carbofuran, a pesticide banned in the U.S. Using conservative numbers, the 32 ounces recovered could kill more than 750 black bears, according to the release.

Officers also found nearly 2,000 pounds of dry fertilizer and 58 pounds of liquid fertilizer.

Sheriff's Office Lt. Steve Knight said investigations into all three sites are underway, and the office currently does not have any suspects.

”There were signs they were there recently,” Knight said.

Knight said the officers witnessed environmental damage at all the sites, citing clear cutting, creek damming and multiple truckloads of plastic pipe removed from the ground.

Deputies found 7,521 growing plants, 4 to 6 feet tall, on U.S. Forest Service land below the Brushy Mountain Lookout on Friday Ridge in Willow Creek on Monday morning.

At the Hoopa Valley site, located in the Supply Creek Watershed, the same team found and eradicated 8,473 growing marijuana plant, 3 to 6 feet tall, on Wednesday morning.

On Thursday morning on U.S. Forest Service land at Le-Terron Flat in Orleans the team found 376 growing plants, 3 to 4 feet tall.

Downey said the sheriff's office began partnering with biologists last year after environmental concerns were raised.

”Our first concern is what it's doing to the environment, but there are also safety issues,” Downey said. “Some of the banned chemicals are highly poisonous to officers in the field and anyone else.”

On May 14, the Humboldt County Board of Supervisors unanimously passed a resolution to urging local businesses to discontinue the sale of anticoagulants. At last week's board meeting, supervisors unanimously voted in support of a statewide anticoagulant rodenticide ban.

Second District Supervisor Estelle Fennell, who proposed the resolution, said she is “pretty shocked” at the amount of rodenticide found this week.

”I think the point needs to be pushed more,” Fennell said. “I find it very discouraging that it's still happening.”

Downey said that the resolution is a good move, but he doesn't think it's helping.

”People who aren't residents of the county don't really care,” he said. “They come in, take what they've grown and their profits and leave.”