He will be patient until lawyers start dropping incendiary accusations. He is known to speak his mind and doesn’t always follow the rules.

And in recent years, Senior U.S. District Judge Paul Magnuson has spent time building legal systems in troubled places such as Rwanda and Kurdistan.

He is also the tri-state water wars judge who will decide the momentous question as to whether metro Atlanta is entitled to use Lake Lanier as its primary source of drinking water.

Convening a high-stakes hearing last week in Jacksonville, Magnuson said he was “kind of happy” that a key issue was finally being truly litigated. “That’s a good thing,” he said.

Whether it’s a good thing for the metro area remains to be seen.

Magnuson’s decision is of enormous consequence for Atlanta’s future water needs and the current needs of Gwinnett County, which draws millions of gallons of water a day from Lake Lanier.

Magnuson, 72, of St. Paul, Minn., was picked in March 2007 to preside over the multidistrict litigation involving Georgia, Alabama and Florida. A panel of federal judges noted that Magnuson previously oversaw litigation involving water rights to the Missouri River.

Raised on a South Dakota farm, Magnuson attended Gustavus Adophus College, a Swedish Lutheran institution in St. Peter, Minn. After law school, Magnuson became the fifth member of a St. Paul law firm that would produce a Minnesota governor, a state Supreme Court justice and a U.S. senator.

In 1981, that senator, Dave Durenberger, got President Ronald Reagan to put Magnuson on the federal bench in Minnesota.

“He’s a quick study and insightful as to where people are coming from,” Durenberger said. “I think it’s also good this decision will come from someone who has no stake in the issue.”

Through a clerk, Magnuson declined an interview request.

In recent years, Magnuson traveled the world to help build judiciaries in Albania, Kazakhstan, Kurdistan and Rwanda.

Lawyers who have practiced before Magnuson say he will speak his mind, such as when he chafed at sentencing guidelines.

In 2001, Magnuson refused to give a lengthy, mandatory prison term to Shellie Langmade for a methamphetamine conspiracy. Langmade, the judge said, would be “sacrificed on the altar of Congress’ obsession” with punishing narcotics offenses.

“I am so embittered by the government’s merciless conduct that I simply could not be impartial,” Magnuson wrote when stepping off the case.

Magnuson calls it like he sees it, said Senior U.S. District Judge Richard Kyle, a colleague in St. Paul. “I don’t think he has any fear of making the tough calls.”

In the Missouri River case, Magnuson ruled in favor of the Corps of Engineers, saying it could operate the river without changes sought by environmentalists to save endangered fish and birds. He was upheld on appeal.

In the tri-state litigation, Magnuson has told the parties he expects them to be candid and forthright. In March, he chided lawyers over inflammatory accusations leveled in legal briefs.

“No party’s position is advanced by the type of slash-and-burn litigation tactics evidenced by these multiple motions,” he wrote. “Perhaps more importantly, the interests of the respective clients … are harmed by the voluminous paperwork and at times vitriolic argument submitted to the court.”

In the tri-state case, Alabama and Florida contend that Lake Lanier has three primary purposes: hydropower generation, river navigation and flood control. The metro area needs congressional approval to tap into Lake Lanier for all the water it needs, lawyers for Alabama and Florida say.

Water supply is only an “incidental” benefit — the metro area can take water that flows through Buford Dam’s hydroelectric turbines, the two states contend. Two federal appeals court rulings support this position.

Lawyers for Georgia and the Atlanta Regional Commission counter that 1946 legislation authorizing Buford Dam’s construction also made water supply a primary purpose for Lake Lanier.

This issue has never been fully litigated and remains open and undecided, Patricia Barmeyer, an ARC lawyer, told Magnuson. “We urge you to resist the calls from Alabama and Florida … that there’s nothing left for you to decide in this case.”

At Monday’s hearing, Magnuson expressed frustration with the Corps of Engineers for taking decades to determine how to allocate water from Lake Lanier.

But whenever he asked a pointed question, it was most always directed at lawyers for Georgia.

At one point, he asked why Atlanta has not paid for water storage at Lake Lanier.

“There came a time when the corps said to Atlanta, ‘OK, put some money into this thing,’ and Atlanta said ‘No,’ ” Magnuson said. “How do I deal with that?”

Bruce Brown, a lawyer for Georgia, said the city has always been willing to pay its fair share, and as soon as it gets water storage contracts, it will pay for them.

But Alabama’s lawyer, Matt Lembke, showed the judge a letter then-Atlanta Mayor William Hartsfield wrote to James C. Davis, a Georgia congressman, in 1948.

Water supply from Lake Lanier “is only incidental and in case of a prolonged drought,” Hartsfield wrote. “Certainly in view of other possible sources of Atlanta’s future water we should not be asked to contribute to a dam which the Army Engineers have said is vitally necessary for navigation and flood control.”

Brown downplayed the missive, saying it was an “internal” letter, not the city’s official position.

But Magnuson didn’t buy it.

“We’re both old enough to know you don’t send anything to Congress that’s an ‘internal’ letter,” he said. “Be prepared to let the world know about it.”