Cannabis farming is changing streams in California, experts warn
Groundwater pumped to irrigate cannabis crops in California's Emerald Triangle can cause some streams that normally run year-round to dry up entirely during summer, say researchers from Simon Fraser University, the University of California, Berkeley and the United States Department of Agriculture.
A new study warns that cannabis farming in California's Emerald Triangle is altering streams, according to experts from Simon Fraser University, the University of California, Berkeley, and the US Department of Agriculture. Groundwater pumping for irrigation in the region's rugged mountainous areas can cause normally year-round streams to dry up entirely during summer droughts, according to the research published in the Journal of Hydrology.
Jesse Hahm, an assistant professor of geography and co-author of the study, emphasizes that groundwater and streams are interconnected parts of the same system. During heat waves and droughts, increased irrigation demand can exacerbate stress on stream ecosystems. The study analyzed 580 scenarios to understand how groundwater pumping and environmental conditions affect streamflow, finding that in dry years and watersheds with limited water-storage capacity, pumping can shorten the flow duration of seasonal streams by up to five weeks.
Even small shares of cultivated land within a watershed can lead to measurable impacts on streamflow. These findings highlight the need for better understanding of how groundwater pumping influences streamflow higher up in water systems to balance agricultural needs with environmental protection, particularly for salmon habitats and downstream water supplies.
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