Hall County officials, in their pursuit of a new reservoir upstream of Lake Lanier, want to make sure the U.S. Army Corps of Engineers doesn’t confuse their plans.In a letter written late last week, Tom Oliver, chairman of the Board of Commissioners, told the corps the county’s plans to release water from the proposed Glades Reservoir into Lake Lanier are meant to add to the allocation of water for the Gainesville Public Utilities Department, not to replace it.The corps is currently evaluating the environmental and social impacts of building the county’s reservoir. The county’s ability to dam up a portion of Flat Creek, a tributary of the Chattahoochee River, to store enough water to provide the county with about 70 million gallons of water a day depends upon the corps’ approval.Originally, county officials said they planned to pump the water from the Chattahoochee River to an existing reservoir in the Oconee River basin. Cedar Creek Reservoir, however, had been at the center of a dispute between officials in Gainesville and the county.But on Aug. 10, county officials said a recent decision by the U.S. Supreme Court — which decided to let an appeals court ruling that drinking water was an authorized use of Lake Lanier stand in the decades-long dispute between Georgia, Florida and Alabama — allowed them to send the water from their proposed reservoir straight to Lake Lanier.There, the water can be withdrawn and treated by existing plants owned by Gainesville’s Public Utilities Department.The revised plan is supposed to reduce the projected cost of building Glades by $200 million to $95 million, county officials say.Oliver wrote another letter to the corps on Aug. 23 clarifying the county’s new plan to send Glades’ water to Lanier and have Gainesville treat and distribute it.“The Glades Reservoir Project is not proposed to replace Gainesville’s existing and future Lake Lanier permitted direct withdrawal allocations, but is to be used only to supplement the permitted direct withdrawal allocations,” Oliver wrote.Reached Wednesday, Oliver said the letter was to make sure the county communicated its intentions clearly.“We’re still going to work with the local municipalities,” Oliver said.Kelly Randall, the director of Gainesville’s Public Utilities Department, said the letter came after the city questioned the county’s revised plan.“When they sent the (Aug. 10) letter out, we read it and had one question, and they just said ‘Oh well, we’ll just write a letter about it,’’’ Randall said.