Utah lawmakers rode golf carts eight miles through a tunnel beneath the Uinta Mountains to see where Wasatch Front drinking water begins. The trip underscored what's at stake as a fight over the Colorado River intensifies with no multi-state deal in sight.

Members of the Utah State Legislature toured the Central Utah Project (CUP) in late October, driving more than an hour through a passage buried 3,000 feet underground before emerging at Upper Stillwater Dam, Fox 13 News reported. The CUP captures snowmelt at Upper Stillwater Reservoir and delivers it by gravity through the tunnel to Strawberry Reservoir, then to the Wasatch Front through Spanish Fork Canyon.

The project provides as much as 25% of the Wasatch Front's drinking water, according to Fox 13. That water reaches Salt Lake County as far north as the state Capitol and the airport, said Dylan Dastrup, the Stillwater area manager for the Central Utah Water Conservancy District.

"Utah and Salt Lake counties are the Colorado River," Dastrup told Fox 13. "When we're conserving water out there? We're conserving the Colorado River."

Lawmakers push for state cooperation

Rep. David Shallenberger, R-Orem, called the infrastructure "incredible engineering feats" and said the Colorado River is vital for Utah and its neighboring states.

Sen. Ron Winterton, R-Roosevelt, has a personal connection to the project. He helped build the dam as a contractor.

"Without this project here? The Salt Lake Valley wouldn't be able to grow how it has," Winterton told Fox 13.

Duchesne Mayor Deborah Herron, who attended the tour, said her city depends entirely on water stored in Starvation Reservoir, another piece of the CUP system.

Federal control and lawsuits

Colorado River basin states have failed to agree on new rules for sharing the river, which serves more than 40 million people across the West. With no deal, the U.S. Bureau of Reclamation is managing the river under a federal plan signed by Interior Secretary Doug Burgum.

Nevada filed a federal lawsuit on Aug. 24 challenging that plan. Arizona moved to intervene in the suit on Oct. 16, according to the Arizona Republic. Arizona Department of Water Resources Director Tom Buschatzke said the federal framework "ignores basic elements of the Law of the River" and could devastate Arizona's economy. The two states' interests do not fully overlap, according to the filing.

The federal plan would cut 1.25 million acre-feet of water deliveries to the Lower Basin states in each of the next two years. Arizona alone faces a 760,000 acre-foot reduction..

Dastrup said Wasatch Front residents focused on the Great Salt Lake should also watch the Colorado River closely, because it is their water supply too.

Current river management guidelines expire Dec. 31.