Contractors inadvertently struck an unmarked line believed to have once served the former Save A Lot store, now home to City Hall.
The affected area extends from South Weldon to Main Street and from Moore Street to West Carlisle, which includes the Crittenden County Detention Center and the Crittenden County Public Library.
The advisory will remain in effect until further notice and lifted by city officials. Residents in the impacted zone are advised to boil water for drinking and food preparation.