A warning not to drink the water in a Colorado town has been canceled, after tests showed there was no longer any evidence of a marijuana chemical in the tap water, an initial finding which the mayor said “blew his mind”.

The Lincoln County sheriff’s office said on Saturday that a criminal investigation was continuing into suspected tampering and forced entry at a Hugo community well. The investigation has been turned over to the Colorado bureau of investigation, the sheriff’s office said.

Bottled water was distributed to residents of the town after officials said on Thursday that some field tests had found THC, marijuana’s psychoactive ingredient, in the water. More tests were ordered.

The mayor of Hugo, Tom Lee, told the Denver Post he was shocked by the news and added that the town had not seen any acrimonious debate over marijuana since the drug became legal in the state in 2012.

“We’ll figure it out,” Lee told the Post, adding of the news: “It just blew my mind.”

No illnesses have been linked to the water in Hugo, a town of about 730 people some 100 miles south-east of Denver, according to the Lincoln County public health director, Susan Kelly.

In a statement, the Lincoln County health officer Dr John Fox said: “It would take more product than any of us could afford to contaminate a city water supply to the extent that people would suffer any effects.”

Peter Perrone, owner of a cannabis testing facility, Gobi Analytical, told the Post cannabinoids such as TH “are in no way soluble in water”.

“There is zero possibility that there’s anything like THC in the Hugo water,” Perrone said.