The Latest on the discovery of marijuana's active ingredient in the water supply at in a small Colorado town (all times local):

7:40 p.m.

Authorities say they found signs that a water well had been tampered with after preliminary tests showed the psychoactive chemical in marijuana was present in the drinking water of a small Colorado town.

Residents of Hugo, about 100 miles southeast of Denver, were told Thursday not to drink the water or shower in it because of evidence of THC, marijuana's intoxicating ingredient.

Lincoln County Public Health Director Susan Kelly says no illnesses have been linked to the suspected contamination.

She says bottled water is being trucked in, and a tanker full of water is on the way.

Sheriff's Capt. Michael Yowell says only field tests have been conducted on the water, but more extensive testing is underway.

Yowell says the FBI and the Colorado Bureau of Investigation are helping with the case.

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4 p.m.

Officials in a small Colorado town say well water has been contaminated with marijuana's psychoactive chemical.

Authorities are telling residents of Hugo, about 100 miles southeast of Denver, not to shower or drink the water because of evidence of marijuana's intoxicating ingredient THC.

A spokeswoman for the Colorado Division of Emergency Management, Micki Trost, says state investigators are headed to the scene.

She did not know the source or extent of the contamination. The Lincoln County sheriff's office says federal authorities are also involved.

Hugo, a community of about 730 people, prohibits marijuana cultivation, product manufacturing, testing facilities, and Colorado's retail marijuana stores.