LOS ANGELES — Two months after two men were arrested at an illicit marijuana farm on public land deep in the Northern California wilderness, authorities are assessing the environmental impact and cleanup costs at the site where trees were clear-cut, waterways were diverted, and the ground was littered with open containers of fertilizer and rodenticide.

A group including U.S. Forest Service rangers, local law enforcement, scientists and conservationists hiked into the so-called trespass grow where nearly 9,000 cannabis plants were illegally cultivated on national forest land in the region known as the Emerald Triangle, for the marijuana that has been produced there for decades.

Authorities allege members of an international drug trafficking ring set up camp at the site as far back as 2015.

When deputies raided the remote clearing in the woods Sept. 9, they found hundreds of pounds of harvested marijuana, thousands of pounds of trash and more than 3 miles (4.8 kilometers) of plastic irrigation piping, according to the Trinity County Sheriff’s Office. They also discovered bottles of carbofuran, a banned neurotoxicant used to kill rodents that also has been linked to the deaths of spotted owls, fish and mountain lions. A quarter-teaspoon can kill a 300-pound (136-kilogram) bear.

The case highlights some of the growing pains California has faced since kicking off broad legal sales in 2018. Its legal marijuana market has grown to more than $3 billion but remains dwarfed by a thriving illegal market, which rakes in nearly $9 billion annually. Limited resources mean officials can’t keep up with all the illegal sites that are remnants of the outlaw era, when much of the pot for the U.S. black market came from the Emerald Triangle.

Experts say illegal sites like the one found in the Shasta Trinity National Forest, about 100 miles (160 kilometers) from the Oregon line, siphon valuable water, pollute legal downstream grows and funnel potentially tainted cannabis onto the streets.