HispanicBusiness

California's annual medical marijuana harvest is just about done, but this year brings a new revelation sweeping the nascent industry: The feel-good herb may not, in fact, be so good for the environment.

From golden Sierra foothills to forested coastal mountains, an explosion of pseudo-legal medical marijuana farms has dramatically changed the state's landscape over the past two years.

A rush to profit from patient demand for pot has resulted in irresponsible forest clearing, illegal stream diversions, and careless pesticide and fertilizer use that has polluted waterways and killed wildlife, state and local government officials said.

The problem has become so big and so unregulated that the California Department of Fish and Game has resorted to aerial surveys to assess its scale. It has a new high-resolution, computer-controlled camera mounted in the belly of an aircraft to help pinpoint problem marijuana areas.

In a recent flight over Nevada County, game warden Jerry Karnow was "astounded" at the increase in obvious marijuana grows visible from the air. They pop out as tightly clustered patches of vivid green plants in an otherwise sun-baked landscape, usually surrounded by tall fences.

In the course of a 90-minute flight, the visible grows numbered in the hundreds, often carved out of mixed oak and pine forests on steep, erosion-prone hillsides.

"I flew this last year and I'm seeing a whole bunch more than I did then," said Karnow, a warden in the region for 15 years. "This year it was unbelievable."

Medical marijuana grows fall into a different category from illegal "trespass grows," which tend to be hidden on public land and maintained by criminal organizations. Pot grown for medicinal use is found on private land and legally permitted under state law.

But the environmental problems they create are similar, in large part because the state's ability to regulate marijuana cultivation remains hazy. Though state law makes it legal to grow and use medical marijuana, it provides little guidance on how to regulate it.

In addition, medicinal grows remain illegal under federal law, putting state and local agencies on uncertain ground when they attempt to set limits.

"The impacts 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," said Mark Lovelace, a Humboldt County supervisor who is grappling with the dilemma.

"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 when they approved Proposition 215. The law allowed patients with a doctor's recommendation to possess and grow marijuana in limited quantities, but did not set clear limits.

The Legislature tried to fix that loophole with Senate Bill 420, which took effect in 2004. It allowed Proposition 215 patients to cultivate no more than six mature or 12 immature plants. But the law was challenged in the state Supreme Court, which ruled in 2010 that the limit on plant numbers was invalid.

Many growers took this as endorsement to cultivate all the marijuana they wanted. This may have triggered the explosion of medicinal grow sites across the state that is now prompting environmental concern.