The Nevada Supreme Court dealt a huge blow Thursday to Las Vegas officials’ controversial plan to siphon water from the state’s rural north, saying that a faulty application process invalidates the south's claim to tens of thousands of acre-feet of water.

Starting in 1989, Las Vegas-area water officials – anticipating a massive population boom in thirsty southern Nevada – asked the state water engineer for groundwater rights in a number of rural valleys. Critics panned the proposal to channel water, via a 300-mile pipeline, from ranching to casino country as an Owens Valley-like grab. A number of people filed formal objections.

“It was very much a way to just lock up this water,” said Simeon Herskovits, the lead attorney for protesters including the Great Basin Water Network.

The state engineer was required by law to move on the water rights applications within a year. Nothing happened until 2005. As the state engineer began to consider the water requests, dozens of people, including the relatives of northern landowners who had died since the applications were first filed, tried to lodge formal objections. They were denied.

The state Supreme Court ruling sends the parties back to a District Court, which will decide whether the Southern Nevada Water Authority (SNWA) must start the application process anew, as the protesters would like. Alternately, the court could recommend that the state engineer simply reopen the formal protest period.