In one of the worst droughts in history, illegal marijuana growers are taking uncontrolled amounts of water across the western United States, leaving little behind even for licensed users.

This is especially true in Oregon, which recently experienced one of its driest springs in nearly a century.

While water politics have existed in the region for a long time, illegal marijuana farms continue to expand in Western states, putting a strain on the supply. According to the Cannabis Research Center at the University of California, Berkeley, California, which legalized recreational marijuana in 2016, there are more illicit cannabis farms than licensed ones.

Some jurisdictions are retaliating. In May, the Siskiyou County Board of Supervisors in California prohibited trucks carrying 100 gallons or more of water from using roads leading to arid tracts where 2,000 illegal marijuana grows were allegedly using millions of gallons of water daily.

In 1972, Jack Dwyer moved to an idyllic, tree-studded parcel in Oregon with a Deer Creek running through it to pursue a dream of returning to the land.

However, Deer Creek is now dry after several illegal marijuana grows sprouted up in the area last spring, stealing water from both the stream and nearby aquifers and jeopardizing Dwyer’s future. The number of illegal grows in Oregon appears to have increased recently, as the Pacific Northwest experienced its driest spring since 1924.

According to Mark Pettinger, spokesman for the Oregon Liquor and Cannabis Commission, many are operating under the guise of hemp farms, which were legalized nationally under the 2018 Farm Bill. The maximum THC content of hemp—the compound that gives cannabis its high—must be less than 0.3 percent, according to the law. Hemp plant fibers are used to make rope, clothing, paper, and other products.

According to Josephine County Sheriff Dave Daniel, there are hundreds of illegal grows in his southern Oregon county alone, many of which are funded by foreign funds. He believes the financiers anticipate a few losses, but the sheer number of them ensures that many will last until the marijuana is harvested and sold on the black market outside of Oregon.

According to Pettinger, none of the new sites have been licensed to grow recreational marijuana. Regulators, faced with a backlog of license applications and a glut of regulated marijuana in 2019, halted new application processing until January 2022.

According to Daniel, the illegal grows have had “catastrophic” effects on natural water resources. Several creeks have dried up much sooner than usual, and the water table—the underground boundary between water-saturated soil and unsaturated soil—is falling.

Last month, Daniel and his deputies, aided by other law enforcement officers, destroyed 72,000 marijuana plants growing in 400 hoop houses, which are cheaply constructed greenhouses.

The water for those plants came from the nearby Illinois River, which is part of the Wild and Scenic Rivers System, which was established by Congress to protect rivers with outstanding natural, cultural, and recreational values. Dwyer has a water right to Deer Creek near Selma, which allows him to grow crops. The creek can sometimes run dry late in the year, but Dwyer has never seen it this dry, let alone this early in the year.

Dwyer built an infrastructure of buried water pipe, a dozen spigots, and an irrigation system connected to the creek over the years to grow vegetables and protect his home from wildfires. He gets his water from an old well, but it’s unclear how long that will last.

Marijuana has been grown in southern Oregon for decades, but the recent explosion of massive illegal grows has shocked residents. The Illinois Valley Soil and Water Conservation District, where Dwyer lives, recently held two town hall meetings on the subject. According to Christopher Hall, the conservation district’s community organizer, the main concern was water theft.

Rodger Jincks of La Pine, Oregon, stood by as a crew drilled a new well on his property. The first indication that his existing well was failing came when the pressure dropped while he was watering his tiny front lawn. According to Driller Shane Harris, the water table is dropping 6 inches per year.