Everybody in Charlotte knows Lake Norman and Lake Wylie, but those popular boating spots are actually part of a 300-mile river that stretches from the Blue Ridge Mountains to the Atlantic Ocean. It's called the Catawba River and it's a main source of water in North and South Carolina. It's also at the heart of an historic fight playing out in the U.S. Supreme Court. Part of the case goes to oral arguments on Monday. WFAE's Julie Rose has more: Out West there's a saying, "Whiskey's for drinking. Water's for fighting over." And South Carolina Attorney General Henry McMaster has thrown the first punch. He says he's tried to reason with North Carolina about the millions of gallons it siphons from the Catawba River every day, but got nowhere. "We had one option left, and that was to take it to court," says McMaster. And not just any court. McMaster is challenging North Carolina to a showdown over water in the U.S. Supreme Court. The court agreed to hear the case, like it has for a handful of Western states over the years. But lawsuits over water were practically nonexistent between Eastern states until just a few years ago, because we all pretty much thought the rivers would flow forever. Then came the drought of 2007. McMaster saw rivers and creeks shriveling up all over South Carolina and started worrying about the future. You could say the drought turned him from a Southern gentleman into a frontier sheriff out for justice. "For the health of the state, we need to have water and to be sure that our share of that river comes across the border," says McMaster. Don't be fooled by the measured tone in his voice. McMaster has an intimidating stare. The trouble is, he doesn't have much proof that North Carolina's use of the Catawba has actually hurt his state. "But the real threat is what they may do in the future," says McMaster. "Under the current state of the law in North Carolina the Environmental Management Commission could keep issuing permits right on from now until eternity - until the river is completely dry before it comes across the border if they wanted to - and there's nothing to stop 'em." Technically, that's true. Eastern states follow a common law known as the "riparian system" that assumes there's plenty of water to go around. Folks upstream are just expected to be reasonable in their use. But that law was established in Colonial times - before drought, climate change and explosive population growth came to the Southeast. Being downriver in a situation like that is not good. So McMaster wants the Supreme Court to tell North Carolina how much water it's allowed to take from the Catawba. On a map splayed across his conference table, McMaster traces the blue line of the river with his finger - and then draws a bulls-eye around Charlotte. "The city of Charlotte accounts for 53 percent of the municipal usage in this river from top to bottom," says Charlotte City Attorney Mac McCarley. He knows full well McMaster's got the city in his sights. But McCarley says Charlotte's proud of its growth, which requires it to draw tens of millions of gallons from the Catawba River every day. And he insists it's not doing South Carolina any harm. "We've been good stewards of the water," says McCarley. "When we had in various places across our state in the 2007 drought mandatory restrictions in place, South Carolina was only gently moving up to voluntary restrictions. We think we're being very responsible with the use of the water." Charlotte has already spent in excess of a million dollars to argue that point, even though the city is not technically a party in the Supreme Court lawsuit. McCarley says the city will spend whatever it takes. "We are the folks who have the most at stake in this - basically, our right to use the Catawba river now and forever into the future," says McCarley. And because the stakes are so high, Charlotte is asking the Supreme Court to let it join the Catawba water lawsuit as an equal to North and South Carolina. So is Duke Energy, which basically controls the flow of the river with its 13 dams. The company has spent years trying to negotiate with both states for a new federal hydropower license. The Supreme Court will consider their requests on Monday, but environmental law expert Victor Flatt says a decision on who gets what water could take much longer. "It could take five years, it could take ten years," says Flatt. He notes that it's already been two years since South Carolina filed the lawsuit, and so far the court hasn't even decided who should be part of it. Attorney General McMaster thinks Charlotte, Duke and North Carolina are just trying to slow things down so they can have more time to hoard water. But Flatt, who teaches law at UNC-Chapel Hill, says there's no guarantee the court's ultimate decision will be better for South Carolina than the status quo. "There's no legal test for what is 'fair and equitable,'" says Flatt. "They could do whatever they want. And that's the risky part of this. In fact, you know when they start looking at equitable principles, the Supreme Court could even go so far as to elevate some uses over another." So instead of giving South Carolina more water, the Supreme Court could come back and say, "Actually, neither state gets more water. You both have to leave more for the fish." Which brings us to environmental concerns. From inside a courtroom it can be easy to forget the Catawba River is much more than a blue squiggle on a map or a chart of "gallons per day." It has rapids, reservoirs, a flood plain and a collection of rare and endangered wildlife. "This is one of the more dramatic scenes on the river as far as what hydropower dams can do to a functioning river," says Gerrit Jobsis, as he leads me on a short tromp through the weeds to a spot on the Catawba River where dams have turned a once-famous stretch of rapids into a small lake. Jobsis is the Southeast Director of American Rivers. Last year, the environmental group named the Catawba the Most Endangered River in America because of the very thing North and South Carolina are squabbling over. While they drain away more water to make electricity, flush toilets and keep their grass green, Jobsis says neither state has a clear plan "that's going to keep the river a great resource for the people and for the fish and wildlife and not just a remnant of its former self like we see here in front of us." The Supreme Court will try to strike that balance on the Catawba River. And UNC Chapel Hill's Victor Flatt says other Eastern states will be watching closely. "It's a harbinger of things that are coming," says Flatt. "It seems unusual sort of now, but the facts that give rise to this are being repeated over and over again." The water wars of the arid West have officially moved East.