New research suggests groundwater pumping for cannabis irrigation in Northern California’s Emerald Triangle could reduce streamflow in some headwater creeks, particularly during dry years, potentially affecting salmon habitat and downstream water supplies. Under realistic irrigation demands, they found groundwater pumping could cause some seasonal streams to stop flowing as much as five weeks earlier than normal. “We found that in these upland, mountainous landscapes, pumping water from underground can affect streamflow in ways that may not be immediately obvious.” But warmer winters and reduced snowpack are changing the way water is stored and released into the landscape,” says Hahm. “Understanding how groundwater pumping influences streamflow higher up in our water systems can help decision-makers balance agricultural needs with protecting fish habitat and other environmental values.”