Study: North Coast cannabis growers rely more on groundwater amid debate over drought restrictions

A new study has found that cannabis farms in California’s prime growing regions, including the North Coast, rely primarily on groundwater wells to irrigate their crop as opposed to streams, providing more insight into the debate over water scarcity as the state grapples with a historic drought.

The Cannabis Research Center at UC Berkeley report found that well water use by cannabis farms is common statewide, exceeding 75% among farms that have permits to grow in nine of the 11 top cannabis-producing counties that include Sonoma, Mendocino and Lake counties.

The study released this month was compiled from water source data by permitted cannabis farms — though a large percentage of the industry is still in the shadows and unregulated by state and local agencies. The researchers were able to estimate that 60% of the unregulated cannabis farms in the prime growing region of Humboldt and Mendocino counties also use groundwater to irrigate.

“The easiest solution is to drill a well,” said Christopher Dillis, a researcher for the center who worked on the study.

The research comes as local agencies and cities are taking steps to save water during the drought. For example, state regulators plan to suspend water rights for diverters in the upper and lower Russian River. Amid the renewed scrutiny of water usage, some local ranchers are selling their herds and grape growers are letting some vines go fallow this year.

Many of the cannabis farms surveyed in the report were outside of the Sustainable Groundwater Management Act, the 2014 state law that gave local officials more authority to evaluate and regulate groundwater in threatened basins. The degree of those outside of such zones varied among counties. In Sonoma County, only about 30% of its 40 permitted and licensed cannabis acres lie outside of those high-risk basins. That number was more than 50% in Mendocino County and around 66% in Lake County.

Dillis and his team presented their findings to the Mendocino County Board of Supervisors on July 19. At the hearing, Dillis noted that water wells near streams are common and those are difficult to regulate. But those water wells could cause depletion similar to diversions of surface water. “We have kind of put our finger on that one of the things we’re most concerned about,” he told supervisors.

Supervisor Glenn McGourty said he appreciated the information and that he sensed cannabis cultivation is having a greater impact within Mendocino County in the upper watershed than those farms in the groundwater basin. The UC Berkeley team agreed with that sentiment. McGourty noted that water storage could play a role going forward for cannabis farmers through the use of ponds and “it could be filled with wells in the winter when the impact is not so strong.”

Michael Katz, executive director of the Mendocino Cannabis Alliance, said he appreciated the research and noted that the center has found that “licensed cannabis uses way less water than many in government and the public realize.” The center has found that cannabis water usage is similar to vegetable crops as the average for northern California outdoor cultivation is 1.5 acre-feet per year. (An average household uses between 0.5 and one acre-foot per year, according to the Sacramento-based Water Education Foundation.)

Katz endorsed more pond building for licensed cannabis operators to assist with better water storage. He said Mendocino County recently passed an emergency ordinance to allow the installation of emergency water tanks and asked supervisors to pass another ordinance to streamline the approval of irrigation ponds and other storage methods “to enable cannabis and other agricultural operators to prepare for the new realities of climate change.”

Those in the cannabis industry are on guard over the debate on water usage as they note their crop is monitored much more than any other because of state licensing requirements. Local authorities may place their own restrictions as well. In Sonoma County, water hauling for cannabis growing is only allowed under a use permit, said Sue Ostrom, assistant agricultural commissioner.

“We as an industry are not interested in being scapegoated,” said Joanna Cedar of the Sonoma County Growers Alliance.