A Threat to the Environment

Outdoor marijuana cultivation sites are becoming increasingly common. These "grows" often result in the destruction of natural habitat from diesel spills, pesticide runoff, and trash from cultivators.24 National parks and other public lands in the United States are used for cannabis cultivation operations, primarily by Mexican criminal groups. Data from the Department of Agriculture Forest Service and the Department of the Interior indicate that more than 4 million marijuana plants were eradicated from U.S. public lands in 2008 alone.

"The Administration steadfastly opposes legalization of marijuana and other drugs because legalization would increase the availability and use of illicit drugs, and pose significant health and safety risks to all Americans, particularly young people."
Whitehouse.gov