MARIETTA — Leaders of the Cobb County-Marietta Water Authority say they will consider buying out the City of Canton’s 25 percent stake in the new Hickory Log Creek Reservoir in north Canton. That would make the authority the sole owner of the 400-acre reservoir.

The authority is a wholesaler and sells water to retailers like the Cobb County Water System and the cities of Marietta and Smyrna.

In May 2000, the water authority and the city of Canton agreed to a 50-year partnership to build the pumped-storage reservoir, and the conceptual cost estimate was $20 million to build.

But that cost ballooned, in part, amid increasing land costs. The owners have spent about $5 million to buy mitigating properties to offset effects to wetlands, streams and endangered species by the project, said Glenn Page, general manager of the water authority.

“I expect that the entire project will be delivered under $100 million,” Page said. “Then, operational expenses are in the range of $750,000 per year.”

Smyrna Mayor Max Bacon, who chairs the water authority, said that despite the cost, the reservoir is “absolutely” needed.

“The bottom line is, we do have a reservoir, which is very difficult to get a permit on,” he said.

With Canton, Bacon said, “We’re interested in the point of we’d have discussions, but I think this is the first move they’ve made toward that. We’ll have to see what’s best for our customers.”

The project includes a dam built on the Etowah River that pumps river water to the reservoir. A small creek also feeds the reservoir.

“It’s managed like you do your banking,” Page said. “You keep most of your money that you need on a daily basis in a checking account, but if you’ve got some you’re setting aside for a rainy day — in our case, for a dry day — you put that in savings. The reservoir is our savings. We’re taking water out of the Etowah to save it for a dry day.”

But the reservoir’s purpose is also for future water supply — and the city of Canton wants to preserve that part of its deal.

Canton has proposed that the water authority take over full operations of the reservoir and assume Canton’s $28 million debt for its share in the project. But Canton apparently still wants the right to use 6 million gallons of water per day from the reservoir, once the Army Corps of Engineers has signed off on such withdrawals.

Page also said that while the reservoir’s cost has affected the rates it charges to the water retailers — which are ultimately passed along to citizens in Cobb and Paulding counties, the city of Marietta and Smyrna, and parts of Cherokee, Fulton and Douglas counties — it has not been any higher than other authority projects.

“The increase in cost of that project has affected our rates, but no more than other projects we’ve had to do to meet regulatory obligations,” Page said. “Right now, we’re doing improvements at our Acworth plant in the range of $100 million.”