New Science Brief about Cannabis Water usage

Researchers find that keeping cannabis farms in the licensed market is key for preventing impacts to streams in Northern California

Read our new science brief, Water Use: Cannabis in Context!   

Our watershed scientists have been exploring how the water use footprint of licensed cannabis compares to unlicensed cannabis water demand, residential water demand, and available stream flow.

After reviewing data from Humboldt and Mendocino County watersheds, our findings and recommendations are as follows:

Water use by cannabis farms represents a small fraction (<1%) of natural surface water supplies in most watersheds.

The majority of water demand for cannabis cultivation comes from unlicensed farms, rather than licensed farms, particularly during the dry season (June – September)

Water storage by cannabis farms shifts the timing of water withdrawals away from the dry season, and has been an effective management practice for reducing impacts to surface flow.

Providing incentives for farmers to increase off-stream storage for irrigation is a key strategy for reducing water extraction during the dry season.

Disincentivizing cannabis farms from participating in the licensed industry will likely only exacerbate impacts to dry season stream flows, as unlicensed farms are less likely to utilize water storage to satisfy dry season irrigation demands



Citation: Dillis, C., Butsic, V., Georgakakos, P., Grantham, T.. 2024. Water Use: Cannabis in Context. Cannabis Research Center, University of California, Berkeley, CA.

Interstate Commerce & the Future of Cannabis

FEB 27 | Webinar


Don’t miss our first webinar of the semester!



New Director Announcement

A message from incoming Director, Michael Polson.

      In 2017,  just a year after California voters approved adult-use cannabis, I remember gathering with a small group of Berkeley scholars. We knew this was an important opportunity to open the door onto cannabis research. Legalization was advancing rapidly but we still did not know much about cannabis, its cultivation, or the social and ecological dynamics surrounding it.  This blindspot was a product of a century of prohibition, now coming to a close in California. Once again, humans were crafting a new relationship with a plant that has been traveling alongside us for 12,000 years.

We saw the need for a hub for cannabis-related research to address knowledge gaps and to grapple with the enormity of the moment.

In the six years that have elapsed, we have become a thriving hub of two dozen researchers, ranging from hydrologists and wildlife scientists to anthropologists, political ecologists and legal scholars. We have built an interdisciplinary, collegial center and tackled some of the thorniest, most pressing issues related to cannabis and its cultivation — from water use and land change to the effectiveness of local regulatory programs and tribal consultations to basic barriers to compliance and the everyday legacy of the drug war in the present.

We’ve published nearly 40 papers, held multiple research briefings, issued a suite of publicly-accessible educational materials, advised policymakers, reporters and advocates alike. We’ve fostered a generation of new scholars, myself included.

As I enter into the directorship, the Berkeley Cannabis Research Center stands on solid ground, thanks to the diligent and dedicated work of our previous directors – Van Butsic and Ted Grantham (and the work of Eric Biber for the first several years). They fostered a wonderful atmosphere of collaboration, robust research, and a rare penchant for engaging the public in all that we do. I look forward to deepening our work in California, which is still the largest political entity to legalize cannabis in the world and a global, historic center of cannabis cultivation. As we grow in scope and scale, we welcome new affiliate researchers, new organizational collaborations, and renewed engagements with the people of California, the U.S. and the globe. I’m proud to be part of the Center and contributing to the mission of UC Berkeley to serve the public.                      

Michael R. Polson, PhD

Parting words from outgoing Directors

      Over the last five years, Berkeley’s Cannabis Research Center has engaged with the most pressing issues surrounding the cultivation and regulation of cannabis in California, including concerns over impacts to the environment, effects of local, state, and national policies on cannabis production patterns, and the lived experiences of cannabis-growing communities.

We have built a reputation for rigor, scholarly discipline, and relevance. We endeavored to elevate questions around cannabis to serious scientific and policy realms, and largely we have succeeded. 

 While the story of cannabis in California continues to unfold, we are excited to be entering a new chapter at the Cannabis Research Center. It is an absolute pleasure to welcome Dr. Michael Polson as the new Center Director. Although Michael is new to the role, he has been a critical team member since the very founding of the Center. Indeed, whenever we want to know what is really going on in the world of cannabis, Michael is the first person to ask. His research on the dynamic interplay between cannabis policies, perceptions, and human behavior has helped all of us better understand the history of cannabis in California, and where it may be going next. There is no one better suited to lead the Center into the future.

As we step back from our leadership roles,  we also reflect on how we first began our work on cannabis: Learning about weed is fun! Our conversations with researchers, government staff, industry representatives, growers, and community groups over the past several years have consistently been enjoyable, stimulating, and meaningful.

We are proud of our research accomplishments – including 40+ resources such as  published articles, research fact sheets and cannabis webinars – but we are most excited by the network of colleagues that we’ve built around the Center. We look forward to staying engaged with the Center’s community as we collectively strive to understand and shape a future of cannabis that supports prosperous, equitable communities and healthy environments – while also having a little fun along the way.

Ted Grantham and Van Butsic 


Research Grants from

the Department of Cannabis Control

Grants awarded to UC Berkeley in 2023 from our state’s cannabis regulatory body, the Department of Cannabis Control (DCC)

We will start our investigations in 2024:

1. Understanding Investment, Operating Pressures, and Anti-Competitive Characteristics in the Cannabis Industry.

Summary: This project will examine whether and to what degree monopolistic and anti-competitive tendencies are emerging in the cannabis industry, the overall patterns of investment and ownership that threaten the competitive landscape of the California cannabis economy, the protective factors that enable small and equity businesses to withstand predatory behaviors, and the current and potential policies that are effective in preventing anti-competitive behaviors.


2. Licensed and Unlicensed Cultivation Across Banned and Permitted Jurisdictions.

Summary: This study will provide the first empirical assessments of unlicensed production amounts and geography over time; identify what policies are correlated with growth or diminution of unlicensed cultivation; estimate total unlicensed market product, including leakage from the licensed to unlicensed market; and test whether cultivation bans or permits are more effective at preventing unlicensed cultivation and environmental harms.


3. Hmong diasporas and cannabis: medicinal use, criminal justice consequences, and farm structure across licensed and unlicensed geographies.

Summary: Hmong farmers have become central in debates about cannabis cultivation and medical cannabis access in California. This community engaged research builds on 6+ years of relationship and trust building with Hmong farmers who grow crops that include cannabis. The research will explore four themes: 1) Hmong medicinal cannabis uses, cultivation practices, and traditional ethnobotanical and medicinal plant histories; 2) Hmong farmer migrations and diasporas; 3) Hmong interactions with criminal justice systems, particularly environmentally based law enforcement; and 4) capital and labor dynamics on Hmong cannabis farms. Research will be primarily ethnographic and participatory, using methods such as in-depth interviews and photovoice. In addition to both ban and permit localities in California, we will conduct research activities in other regions to query Hmong diasporas and agrarian migrations, such as Minnesota, Oklahoma, and North Carolina.