The Smithsonsian write, “Illegal growers are poisoning California’s forests with pesticides, but even legal weed has a carbon footprint

Here’s the introduction to their piece

Mourad Gabriel, an IREC wildlife disease ecologist, tells NPR that he’s already seeing signs of contamination in aquatic ecosystems as well. Grow sites located uphill run the risk of poisoning nearby waterways with chemical runoff. What’s more, JSTOR Daily’s Helmer reports that trespassing growers will often divert water from streams to irrigate their plants, threatening local fish populations.

But even legal cannabis growing outfits have a high environmental toll. Cannabis a particularly thirsty plant, so the water cost is not limited to outdoor operations or illegal growing. Each individual plant requires almost six gallons of water per day, reports Clayton Aldern for Grist. That’s two gallons more than it takes to run one load in an energy-efficient dishwasher. To limit water use, the California State Water Resources Control Board has established strict guidelines, with prohibitions on using surface water for irrigation during the dry season, JSTOR Daily reports.

That’s not the only environmentally-conscious regulation on the legal weed industry. JSTOR Daily reports that growing cannabis can contribute to air pollution, as cannabis plants emit volatile organic compounds that contribute to ground-level ozone, or smog, which is dangerous for humans to breathe. Cannabis growers in Washington state are required to submit plans for how they intend to mitigate the air pollution that comes with outdoor cannabis growth. And in Colorado, the Department of Public Health and Environment is tracking water and energy used, as well as waste created, by the cannabis industry, report Brenna Goth and Tripp Baltz for Bloomberg Environment.

While outdoor cannabis grow sites threaten animals’ habitats, indoor cultivation comes with a massive carbon footprint. Bloomberg reports that legal cannabis production in the United States consumes enough electricity annually to power 92,500 homes for a year. That’s 472 tons of electricity-related carbon—and the number is growing as the industry expands.

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