Raleigh, N.C. — Raleigh leaders are investigating whether waterfowl could be responsible for elevated bacteria levels at Lake Wheeler that have curtailed activities.

Two sites at the lake recently tested show high levels of bacteria. Levels spiked last June, after eight million gallons of sewage spilled from a Cary line into the lake's main water source and forced park officials to block off the water for eight days.

Raleigh Public Works officials said they can't say for sure if the current elevated levels were caused by last year’s sewage spill, but it’s being investigating as a possibility.

Officials are also looking into other sources, such as bird droppings. Public Works employees have begun counting birds at all the city’s waterways.

"The average goose could put out one to three pounds (of waste) daily,” said Richard Costello, of the Raleigh Parks and Recreation Department. “You start adding that up (and there could be a problem.)”

The potentially harmful bacteria have kept visitors from enjoying some activities at the lake several times in past months.

"The restrictions that are still in place are primary contact, meaning skiing tubing, kayaking -- really anything that will involve someone being completely submerged in the water,” Costello said.

"We would have hoped that it would have been back and recovered,” Costello said. “Right now we're not wanting to rule anything out, all possible causes for continued elevated levels."

Costello said it's too early to say if certain birds will be removed, but that option hasn't been ruled out.

As for the sewage spill in Cary, there's still no official word on how much state officials will fine the town in connection with the spill. In October of 2006, the Division of Water Quality recommended a $45,000 fine, but Cary town leaders are appealing that fine.

Town officials hired two consultants who later said a private contractor was to blame for the spill. Cary officials are currently in negotiations with the contractor over the cost of the cleanup.