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.

For more, see: Medical pot growers ravage California forest habitat