An investigation into the source of a mysterious bubbling on Lake Quassapaug only turned up a few beer cans.

Police were told last week that something was causing bubbling in the north end of the lake near a cove, a few days after a boat had been seen speeding away from the area.

Police said they checked with the Department of Environmental Protection to ensure that no monitoring devices had been placed in the area, but on Friday police had only found a few beer cans. Officials said the bubbling was most likely caused by a naturally occurring underground spring.