Classes were canceled Monday for Yale schools after officials found a positive sample of E. Coli in the city's water last week.
City Manager Richard Adams told KTUL that the sample was the only positive one discovered among others that were collected. But it's that positive sample that made the city go under a voluntary boil order.
Additional water samples were sent Saturday to a lab in Stillwater. Results for the test require a wait period and expect to return Tuesday at the latest.
A previous release from the City of Yale states that the sample was taken from the sewer plant. Cross contamination is a possibility, according to the statement.
Adams said that at this point, it is up to citizens whether or not they want to boil their water. Adams also said he has been in close contact with the Environmental Protection Agency.
Residents that want to remain cautious until results return should bring water to a full rolling boil for a minimum of one minute.
The population of Yale is about 1,200.