CROMONA, Ky. (WYMT) - An oily sheen on a stream in Letcher County has nearby residents scratching their heads, but officials with the Kentucky Division of Water say there is no cause for alarm.

The sheen was found on Bear Branch in the Cromona community. Officials have not yet determined exactly what the substance is, but they believe it is diesel fuel. They say the slick should dissipate before it reaches Whitesburg downstream and should not affect drinking water.

"Even if it were to get as far as Whitesburg, their intakes are below the surface of the water," said Kentucky Division of Water spokeswoman Allison Fleck, "so they would be pulling water from below the surface level, so any oil that might reach them would be floating."

Investigators determined the sheen originated on a property on Austin Road. A contractor has been hired to clean up the site.