The U.S. Forest Service is looking at how much illegal cultivation of marijuana is going on in Colorado's national forests following the recent discovery of more than 14,000 plants growing on the Pike National Forest. Forest Service officials scheduled a news conference Wednesday to discuss the degree to which marijuana is being grown in national forests. They are focusing on public safety and environmental issues.Last Friday, authorities found a marijuana growing operation in the Pike National Forest, near Deckers, that covered an area of two to three football fields. They called it the largest marijuana bust in Colorado history. Two people were arrested.The street value of the 14,500 marijuana plants confiscated was estimated at between $7 and $14 million by drug agents and filled two large dump trucks. The plants had to be ferried to the dump trucks by a Colorado Army National Guard Black Hawk helicopter due to its remote location.A hiker discovered the marijuana garden deep in the forest, about two to three miles off any road. In July, authorities spent more than 24 hours clearing a marijuana growing operation on forest land near Cheesman Reservoir, about 3 to 4 miles away from the other side.. They say the 5,000 plants were valued at about $2.5 million on the street. Authorities say there was an elaborate irrigation system at the site. No suspects have been identified.