The national medical marijuana market was estimated to be worth $1.7 billion in 2011 and is projected to reach $8.9 billion within five years, according to an economic analysis done for the American Cannabis Research Institute.
California authorities say the proliferation of outdoor marijuana plantations in the Santa Cruz Mountains are damaging the environment and increasing the possibility of wildfires.
Cal Fire division chief Rich Sampson says trees have been cut down and left in the woods to clear space for pot gardens, creating a huge danger of fire.
The state fire agency opened about three cases for unlawful timber operations related to marijuana plantations in 2010. Last year, they opened 22 cases.
The Santa Cruz Sentinel also says improper grading and erosion have created wildlife habitat problems. California began to allow medical marijuana in 1996.
Patients can legally possess pot and grow it for personal use. But many growers don't get county permits because federal law prohibits cultivation, possession and sale of marijuana.