State and local officials said an increase in cultivation to meet patient demand for legal pot has resulted in unregulated forest clearing, illegal stream diversions and improper pesticide and fertilizer use that has polluted waterways and killed wildlife, The Sacramento Bee reported.
Legal medical marijuana cultivation is in a different category from illegal "trespass grows," which tend to be hidden on public land and maintained by criminal organizations, but both are creating environmental problems, officials said.
While state law makes it legal to grow and use medical marijuana, it remains illegal under federal law, presenting state and local officials with a dilemma when they attempt to regulate the industry.
The effects of water withdrawal, herbicide and pesticide use, unpermitted grading -- all of these things in any other legal industry would be regulated. And we know how to regulate them," Mark Lovelace, a Humboldt County supervisor, said.
"In this case you can't bring them into compliance because the activity they are doing is fundamentally illegal according to the federal government."
California voters legalized marijuana for medicinal purposes in 1996 but there have been ongoing legal challenges against it.
"The belief is to get what you can while the growing's good because it won't last forever," said Lovelace, who added he supports legal use of medicinal marijuana. "There are a lot of folks out there who just don't care about the environmental harm they are doing."