The Southern Nevada Water Authority, the agency that provides Las Vegas with water, is in the process of building a massive pipeline from the eastern central part of Nevada to Las Vegas. If the state of Nevada authorizes this project, it would help solve a pressing water supply problem for its largest population center: Las Vegas. But it will do so at the expense of less water for existing rural users. This includes Native American tribes who have fought mightily for decades to protect many of Nevada’s rural water sources—including water that plays important cultural roles for the tribes.You might imagine that there would be a clear answer to how the law regulates these critical interests. However, that is not the case. The nature of state powers and rights over the water within their territorial boundaries is unclear—that includes the states’ rights when it comes to its private citizens, neighboring states, and the federal government.