The results are in from a year-long study into how California’s emerging legal cannabis industry might impact the environment.

So long as marijuana growers control water runoff, use renewable energy, grow only in permitted areas and stick to other proposed state regulations, the Department of Food and Agriculture said in an environmental impact report released Thursday that any negative effects should be “less than significant for all natural resource areas analyzed.”

State lawmakers had directed the department in 2015 to prepare the environmental impact report, examining the effects of medical cannabis cultivation on the state’s environment and suggesting ways to mitigate potential problems. And when voters passed Proposition 64 in November, it included a requirement that the department expand its report to include impacts of recreational marijuana cultivation.

The department has been holding meetings up and down the state since the fall, giving the public a chance to share concerns with how the state’s estimated 50,000 cannabis grows affect the environment and to give cultivators a chance to discuss how regulations might effect their industry.

The department’s new CalCannabis Cultivation Licensing division on Thursday released the 484-page report, which covers potential impacts regulated medical and adult use cultivation will have on aesthetics, air quality, noise, water quality and more.

Hezekiah Allen, a Humboldt cultivator who serves as executive director of the California Growers Association, praised the report, saying it will help ensure that the industry will be “held to absolutely the highest standard.”

And once the regulations outlined in the report are in place, Allen predicts the cannabis industry “might grow to be one of the largest sustainable agricultural industries in the state.”

Protecting the environment was the main reason groups such as the Planning and Conservation League supported legalizing and regulating cannabis businesses under Prop. 64.

Costa Mesa Police officers cut down marijuana plants after an illegal grow operation was discovered in a commercial property next to John Wayne Airport. (Photo by Kevin Warn, Contributing Photographer)

Illicit cannabis grows have for decades caused significant damage to California’s waterways, forests and other natural resources.

That damage was recognized in the state budget approved Thursday. The budget set aside $1.5 million to help clean up environmental harm caused by illegal marijuana farms in Humboldt, Mendocino and Trinity counties, which produced an estimated $6 billion in cannabis in 2016. For perspective, the report states the region’s entire agriculture output last year not including cannabis was just $500 million.

If the state continued its current practice of not regulating cultivation, the environmental impact report states the effect would be worse than embracing a regulated industry, since clandestine cultivators would continue to use illegal pesticides, tap illegal energy sources and more.

California likely won’t grow more cannabis under a regulated system, the report states.

It’s estimated that California already produces 60 to 70 percent of all cannabis grown in the United States, according to the report. That was roughly 13.5 million pounds in 2016, including around 650,000 pounds of medical cannabis, 1.85 million pounds of cultivation for in-state nonmedical use and 11 million pounds of cultivation for export outside of the state.

Rather than triggering more cultivation, the report predicts regulating the market will shift that makeup a bit, with more licensed medical production and less black market activity.

The report also considered the impact of allowing either only indoor or only outdoor cultivation. While outdoor grows take much less energy and have less of a carbon footprint, the report notes they present more problems for forest lands, biological resources, noise and more. And while indoor grows eliminate many of those concerns, the report states they require more energy and pose greater fire risks.

Though the impacts shouldn’t be significant, the report anticipates there will still be controversy over a number of issues. That includes the public objecting to odors from grow sites, potential impacts to endangered species and high energy use while growers will likely object to how these new rules will force them to change current practices.

In the end, the report deems the proposed licensing program — which calls for six licenses that permit different cultivation methods — to be the “most environmentally sustainable approach.”

A medical marijuana farm in Mendocino County. (Dan Rosenstrauch/Staff)

Given the advantages the report highlights for outdoor grows, though, Allen hopes that might shape the conversation going forward, with many cities now choosing to only permit indoor grows.

“I think California is going to have to have a really serious conversation about indoor cultivation,” he said.

Along with analyzing environmental impacts, Thursday’s report offers the first overview of proposed regulations for California’s recreational marijuana industry, Allen noted, giving the public a “solid glimpse” of what to expect over the next few months.

Before the report was released, the Department of Food and Agriculture had only addressed regulations for medical marijuana cultivators, with 58 pages of draft rules for that segment of the industry released in April.

Those rules now have to be scrapped, since the state budget passed Thursday included contradictory policies. And rules for recreational cultivators aren’t expected to be released for the first time until this fall, when they’ll be introduced as emergency regulations that immediately take affect.

“This is really probably the most informative document we’re going to see before the rules are in place,” Allen said.

The public can submit comments on the environmental impact report until July 31.

The Department of Food and Agriculture will review all comments and take them into consideration as they develop the final report. Responses to “substantive” comments will be included in that final report, which should be released before the state starts handing out business licenses Jan. 1.

Comments on the environmental impact report can be emailed to or mailed to the attention of Amber Morris, CalCannabis PEIR Comments, at 1220 N Street, Suite 400, Sacramento, CA 95814.

People can also offer comments during one of four upcoming public hearings:

  • 6 to 8 p.m. July 11 at Weaverville Veteran’s Memorial Hall, 101 Memorial Lane, Weaverville
  • 6 to 8 p.m. July 13 at Plumas County Fairgrounds, 204 Fairground Road, Quincy
  • 6 to 8 p.m. July 18 at Monterey Marriott, 350 Calle Principal, Monterey
  • 6 to 8 p.m. July 20, Hilton Mission Valley, 901 Camino del Rio, San Diego