MARIETTA — The Cobb-Marietta Water Authority board is set to fire another volley in its series of letters with the city of Canton over a reservoir they share. And officials said that if the city doesn’t listen this time, they could take legal action.

The letter, approved 7-0 at the water authority board’s Monday meeting, asks the Canton City Council to approve a SCADA computer monitoring system for the new Hickory Log Creek Reservoir before the water authority board meets again July 16.

But the Canton City Council seems more concerned about selling its share of the reservoir than putting the SCADA system, with an estimated $1 million price tag, out for bid.

Water authority board member Don Mabry said he is getting tired of the series of letters between Smyrna Mayor Max Bacon, the water authority’s chairman, and Canton Mayor Gene Hobgood. He is ready to take action and wait for the consequences.

“We need to get the project completed,” Mabry said. “Get it completed and we’ll negotiate the interests of both entities.”

In a May 29 letter, Hobgood said the Council hadn’t decided whether the SCADA system is essential to the reservoir’s management. The city, which owns one quarter of the as-yet-unopened reservoir, with the rest owned by the water authority, would be responsible for paying 25 percent of the SCADA system’s cost.

Water authority general manager Glenn Page said the SCADA is needed because the reservoir’s operator works an 8 a.m. to 4:30 p.m. schedule five days a week, and being able to remotely monitor and operate the dam is essential.

Page said the water authority has worked on the SCADA’s design for two years and has been ready to go out to bid for two months. He said there is urgency to get the project bid soon in order to have it ready for summer 2013, when water demand is highest, because it must be advertised for a month, then construction will take nine months.

“It’s a construction project,” he said. “It doesn’t happen overnight.”

While Page said Canton City Council plans to discuss the SCADA system at its Thursday meeting, water authority board members checked the city’s website to find no mention of the project on the listed agenda during their meeting.

Page said that if Canton doesn’t approve the SCADA system by the water authority’s next meeting, the authority would likely take the case to arbitration, which is called for in Hickory Log Creek’s joint user agreement. According to state law, each side would pick an arbitrator; the two arbitrators would then pick a third arbitrator. Page said the three-person panel would then hear the case and make a binding decision or meet “somewhere in the middle” and give direction about what to do.

In his May 29 letter to Bacon, Hobgood said the council will move forward on authorizing the SCADA’s construction at its own pace. He also asks that the water authority consider giving up its right of first refusal to any sale the city of Canton wants to make on the reservoir.

While Bacon wrote Hobgood last month saying the water authority would consider letting the city sell its share of Hickory Log Creek to the Cherokee County Water and Sewerage Authority, Hobgood wrote back that the city is in a “non-negotiable” position because of the water authority’s refusal to give up its right of first refusal.

Increased expenses have led the city of Canton to sell its share in the reservoir, which has seen its total cost rise to nearly $100 million from $20 million when first planned in 2000. The 414-acre reservoir is designed to deliver water through a 1.5-mile pipeline into the Etowah River, where it would flow into Lake Allatoona where the water authority withdraws water for its customers, which include Cobb and Paulding counties and the cities of Marietta and Smyrna. But the opening of the dam has also been delayed because the Army Corps of Engineers has yet to approve the water authority’s plan for water withdrawal.