 -- The worsening drought in California is taking a toll on citizens, some of whom are stealing water in the middle of the night from fire hydrants, officials said.

The city of Lemoore says at least four fire hydrants have been tampered with and, in one case, the perpetrator didn’t even bother to clean up the evidence.

“There was a hydrant that had a hose on it and whoever was there was left the hose,” Lemoore Public Works Director Dave Wlaschin told ABC station KFSN-TV in Fresno.

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Wlaschin said he’s also aware of people who have filled up tanks of water to sell in other drought-stricken areas.

“We’re concerned about it, we’ve been on an active alert for those types of things, with groundwater supplies what they are and surface water supplies an even greater problem,” he told KFSN.

Lemoore isn’t the only city worried about water theft. Across the state, residents and businesses are under strict orders to conserve.

“Water theft is a big concern, so we’re doing public announcements and have a line to call for reports to the Sheriff’s Department,” Carre Brown, a Mendocino County supervisor, told The Associated Press in February, shortly after the county declared a drought emergency. “All deputies are on the watch.”

Brazen thieves swiped thousands of gallons of water last month from a fire department in North San Juan, California, ABC affiliate KXTV reported, by hooking their truck up to a valve.

Illegal marijuana operations are also contributing to the problem. Authorities recently raided a growing operation in central California they say was illegally siphoning water from streams that supply an American Indian tribe.

Experts say the drought, which has destroyed crops and sparked wildfires for three years, will only get worse. It could become a "megadrought," according to researchers at the University of Arizona and Cornell University.

"A megadrought is a drought that's just as bad, in terms of severity, just as dry as the big droughts of the 20th Century, so think 1930s Dust Bowl, think 1950s drought, but much longer lasting," Toby Ault, a professor at Cornell University, told KABC in Los Angeles.

He stressed the importance of conserving water.

"I think we'd really have to change the way we think about water and the way that we can use water because right now we're on a path that would be unsustainable if we had a drought of 35 years," Ault said.