RANCHO CUCAMONGA >> More than 4,000 pot plants and 100 pounds of cannabis were seized at a marijuana grow operation in the mountains north of here, according to the Sheriff’s Department.

The illegal grow operation negatively impacted the environment around Day Creek Canyon, authorities said Friday.

The sheriff’s marijuana enforcement team worked with the DEA and the state attorney general’s Campaign Against Marijuana Planting, formed to eradicate cultivation camps “that cause deforestation, damage to wildlife habitats, pose danger to our citizens, and hazardous-chemical pollutions,” according to the attorney general’s website.

About a mile north of the city limits, authorities on Thursday morning found 4,278 marijuana plants standing four to seven feet tall in rugged terrain, the Sheriff’s Department said.

Two Mexican nationals were apparently living there and tending to the crops. Investigators found camping equipment and a large amount of trash, according to the sheriff’s statement.

“The suspects cut and...