For the first time, Georgia has a contract formally allowing access to water from Lake Lanier, the supplier of drinking water for more than a million people in metro Atlanta.

The agreement, between Georgia and the U.S. Army Corps of Engineers, allows Gwinnett and Forsyth counties along with Buford, Gainesville and Cumming to pull drinking water from Lake Lanier as long as the lake exists.

The massive lake has been used to supply drinking water for decades without a formal agreement, and there has been federal litigation questioning that use as part of the tri-state water wars involving Georgia, Alabama and Florida.

“It resolves a longstanding problem of water withdrawals,” Cesar Yabor, the chief of public affairs for the United States Army Corps of Engineers’ Mobile district, said of the agreement. “This is obviously an important situation for the state of Georgia.”

Glenn Page, chair of the Metropolitan North Georgia Water Planning District, said the agreement was “one of the biggest steps that we’ve experienced in securing our water future” in 30 years.

“Those of us that live this every day, it wears you down,” said Page, who is also the general manager of the Cobb County-Marietta Water Authority. “We have lived from court hearing to court hearing, we’ve gone from negotiation to negotiation, we have crossed the bridge and it gets pulled out from under us.

“Now, we have a document with signatures.”

Linda MacGregor, Gainesville’s water resources director, called it a “significant event” that solidifies a decision the Corps made in 2017 to let the lake be used for drinking water.

“It removes one uncertainty for the water supply for Georgia,” MacGregor said. “This is very important as a milestone. ... We’ve been using Lake Lanier as a water supply, but the state never had a permanent right to it.”

The state will pay more than $74 million over 30 years for that right. But Chris Manganiello, the water policy director for the Chattahoochee Riverkeeper, said the problem of water access could be solved for much longer than 2050, when projections say metro Atlanta will need more water.

The agreement allows Georgia access to just over 15% of the reservoir’s capacity, or 242 million gallons of water each day when the lake is full. The figure includes already-existing permits for Buford and Gainesville that were given to the cities in exchange for the land that was flooded to create Lake Lanier.

“The amount of water is probably more water than we need,” Manganiello said. “We probably have plenty of water in that lake for a long time, as long as there’s water in it.”

Katie Kirkpatrick, president and CEO of the Metro Atlanta Chamber of Commerce, said in a statement that the contract would allow the state and the region to grow responsibly.

“Metro Atlantans can celebrate a landmark victory for sustainable water supplies with this agreement between Georgia and the federal government,” she said. “Given our region’s excellent record on water conservation through the years, I am confident that our communities will make wise use of this essential resource going forward.”

In addition to drinking, Lake Lanier’s water is used for hydropower, navigation, is popular for recreation and feeds other lakes and rivers to maintain healthy ecosystems.

Katherine Zitsch, managing director of natural resources for the Atlanta Regional Commission, said Lake Lanier has long been the most appropriate source of water for metro Atlanta. In addition to the communities that can draw directly from the lake, other water suppliers in metro Atlanta use water from the Chattahoochee River, which is fed by Lake Lanier.

Zitsch said the agreement was “a long time coming.”

“This is the water supply we have, and we have to make sure it carries us indefinitely,” she said. “We feel really good with this contract.”

In a statement, Gov. Brian Kemp’s press secretary, Mallory Blount, said the contract was “the culmination of years of hard work” dating back to Gov. Nathan Deal’s administration. Blount said it required the work of former U.S. Senators David Perdue and Johnny Isakson negotiating across multiple federal administrations.

Gwinnett County Chairwoman Nicole Love Hendrickson lauded the agreement, calling it “an important milestone.”

The contract resolves a dispute that dates back to 2009, when a U.S. District judge ruled that water supply was not an authorized purpose of Lake Lanier, and threatened to cut off metro Atlanta’s access to the lake.

Two years later, the 11th U.S. Circuit Court of Appeals threw out the so-called Magnuson ruling, declaring that Lake Lanier was indeed intended to slake metro Atlanta’s thirst.

Prior to 2017, the corps’ manual was last updated in 1989 and was the subject of legal challenges from both Florida and Alabama. Lawsuits are still pending, and MacGregor said she expects the new contract to bring additional suits.

Still, Page said the metro board will continue to push the Corps to get credit for steps the region has taken to conserve water, including efforts in Gwinnett County and elsewhere to return treated wastewater to Lake Lanier.

“This is a very large step toward where we need to be,” he said.

Meanwhile, the Supreme Court on Feb. 22 will hear oral arguments for the second time in Florida v. Georgia, a long-running dispute related to how much water Georgia uses from the Apalachicola-Chattahoochee-Flint river basin.