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News, Research

Stream Flows May be Impacted by CA Farms Using Groundwater Irrigation

Bethan Rose

by Bethan Rose

August 30, 2021 08:00 am ET Estimated Read Time: 5 Minutes
Stream Flows May be Impacted by CA Farms Using Groundwater Irrigation

A brand new study fresh out of the Cannabis Research Center at UC Berkeley draws serious attention to the burden that cannabis cultivation imposes on water policy. Specifically, UC Berkeley’s investigative research explores where farmers across California are obtaining water for their green yields.

It goes without saying that recreational cannabis legalization in California, which was enacted in November 2016, has stimulated cultivation efforts. Since cannabis cannot thrive without water—similar to most other plants—growers in California are always scrambling for ways to quench the thirst of their crops.

However, as a state with a fairly dry climate, cannabis cultivators are often left seeking out water sources from rivers and streams. Such tactics can threaten the environment in which fish and other wildlife reside.

“Wells drilled near streams in upland watersheds have the potential to cause rapid streamflow depletion similar to direct surface water diversions,” said the study’s co-author Ted Grantham, who also assumes the role of UC Cooperative Extension specialist and co-director of the Cannabis Research Center.

Water use was studied in 11 California counties that are renowned for churning out the highest amount of cannabis. Namely, those counties are “Humboldt, Lake, Mendocino, Monterey, Nevada, Santa Barbara, Santa Cruz, San Luis Obispo, Sonoma, Trinity, and Yolo”.

In order to carry out their research, the team analyzed state data. What they discovered is that cannabis farms depend mainly on groundwater wells (as opposed to natural streams) for their watering needs. Unfortunately, pumped groundwater can negatively impact wildlife. 

“Most of the cannabis farms fall outside of the groundwater basins regulated under the Sustainable Groundwater Management Act (SGMA), so well use represents an important, but largely unregulated, threat to streams in the region,” Grantham added.

About the Sustainable Groundwater Management Act (SGMA)

Since its enactment in 2014, the SGMA has been working to protect groundwater resources over an extended period of time. The SGMA’s historic passage has been hailed for preventing statewide groundwater loss, as well as preserving water quality. The Act also serves as a protective supply shelter for agriculture, fish, residents, and various types of wildlife.

Composed of a three-bill legislative package—featuring AB 1739 (Dickinson), SB 1168 (Pavley), and SB 1319 (Pavley)—the SGMA is constructed with subsequent state rules. Following its adoption in 2014, former Governor Jerry Brown asserted that “groundwater management in California is best accomplished locally.”

As per the legal language contained in the SGMA, locals are required to establish groundwater sustainability agencies (GSAs). for both high and medium-priority basins. The primary purpose of a GSA is to develop groundwater sustainability plans (GSPs) and put them into practice as a means of reducing overdraft and preventing unwanted results within a 20-year period. 

How Does Cannabis Cultivation Threaten Water Sources?

Previous studies, such as this one, have shed light on the threat that cannabis cultivation may pose to natural water sources. When grown in watersheds, populations of various aquatic species may be imperiled.

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Thankfully, the cannabis industry’s notorious reputation has triggered a paradigm shift for state and county-level water policies. Policies are gradually being amended by policymakers and regulators as a means of staying up-to-date with the newly-regulated market.

The sad fact remains that cannabis farms are challenged with the task of developing adequate water storage infrastructure; this is relevant for both legal and illegal agricultural sites. Water storage infrastructure issues are especially apparent in California, where the rugged farming terrain is often located in remote areas.

UC Berkeley’s recent observation clarifies the risks associated with cannabis irrigation. For example, wells located close to natural streams may trap subsurface flows that, if not captured by farmers, would otherwise serve as a primary water source for other streams.

Researchers Discover that Water Well Use is a Common Practice Among Statewide Cannabis Farms 

Referring to the UC Berkeley study on cannabis farm irrigation reliance, groundwater well use appears to surpass 75% among cannabis plantations that possess growing permits in nine of the 11 leading cannabis cultivation counties. 

Moreover, the researchers determined that, in 8 of the 11 top cannabis-growing counties, more than one-quarter of water well-using agricultural hotspots are based outside of groundwater basins; contingent on state groundwater use regulations. 

Another takeaway from this investigation is that farms growing cannabis over larger acreages of space appear to pump a greater amount of groundwater for irrigation purposes. Comparatively, farms that are located in high rainfall areas and/or with streams on site do not rely on wells as much.

It is important to note that the study only assessed water-source data from cannabis cultivation sites that have received state authorization to grow the high-demand crop.

The study determined that 60% of unregulated Northern California cannabis farms—spread across Humboldt and Mendocino counties—are more likely to utilize groundwater wells if they adhere to the same growing patterns as the regulated industry.

“Our results suggest that proactive steps be taken to address groundwater use in cannabis regulations in California and call for further research into the effects of groundwater use on streamflow, especially outside of large groundwater basins,” concluded the study authors.

Published in Environmental Research Communications, the paper, titled, “Cannabis farms in California rely on wells outside of regulated groundwater basins,” was written by Christopher Dillis, Van Butsic, Jennifer Carah, Samuel C. Zipper, and Grantham.

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