INSIDE THE GUNNISON TUNNEL, THE FIRST MAJOR WATER DIVERSION SYSTEM IN THE U.S. ~ The Colorado Sun

The first bore of the Gunnison Tunnel opened in 1909, becoming a model for moving Western water beneath mountains .

Jason Blevins4

Nov 7, 202

MONTROSE — After more than a half-hour splashing through the dank dark of one of the world’s longest irrigation tunnels, Dennis Veo grins in the sunshine showering the cliffs of the Black Canyon of the Gunnison River. 

“The guys who did this were dang sharp,” says Veo, the operations manager of the Uncompahgre Valley Water Users Association. “The engineering that went into this back in the early 1900s, it’s just hard to wrap your head around.”

The 120-year-old, 5.8-mile tunnel was the largest irrigation tunnel in the country when it opened in 1909. It was also the first major transmountain diversion in the U.S., becoming a model for moving Western water beneath mountains, connecting wet basins with dry deserts. 

Today, the Gunnison Tunnel can move more than 500,000 acre-feet of water a year, more than the entire Eastern Slope draws from the Upper Colorado River Basin.

That water, roughly 1,150 cubic-feet-per-second when filled to the ceiling of the granite-blasted tunnel, irrigates about 83,000 acres for 3,000 members of the Uncompahgre Valley Water Users Association and also delivers water to more than 50,000 people in the three-county Project 7 Water Authority. The water that pours from the Gunnison Tunnel is the lifeblood of the Uncompahgre Valley, flowing through 128 miles of major canals and 438 miles of lateral ditches in Montrose and Delta counties.

“We are the largest diverter of water in Colorado,” says Steve Anderson, the second-generation general manager of the Uncompahgre Valley Water Users Association. “We can take about the same as the entire Front Range takes from the Colorado River. And about the same as the Metropolitan Water District of Southern California takes out of the Colorado River. That is a lot of water.”

An engineering marvel 

In the late 1800s, it became clear that the fickle flows of the Uncompahgre River alone could not irrigate enough acres in the river valley between Delta and Montrose. There were close to 100,000 acres homesteaded by farmers but only enough water to irrigate a fraction of that.  

An ambitious plan to connect the Gunnison River with the Uncompahgre River valley started in the early 1900s, when a pair of intrepid engineers with the local power company and the U.S. Geological Survey descended the Black Canyon of the Gunnison River on rubber air mattresses. With cameras and rudimentary surveying equipment, they searched for a place to build a diversion dam and tunnel. 

The first bore of the Gunnison Tunnel opened in 1909. It was the first major project approved by the Department of the Interior under the 1902 Reclamation Act. More than 26 men died during construction of what was then the longest irrigation tunnel ever built. Countless more workers were maimed. The manual diggers — crews of 30 men working around the clock from both ends of the tunnel — were off by only 6 inches when they met in the middle, Veo said. By 1912, water was flowing through the tunnel and irrigating crops from Delta to Montrose.

In 1973, the American Society of Civil Engineers honored the Gunnison Tunnel as a Historic Civil Engineering Landmark. A few years later it was listed on the National Register of Historic Places.

“What’s amazing about it is, on a good day, if the air flows just right, you can get in there just a little ways and shut the lights out and you can actually see the light at the other end,” says Veo, standing on the banks of the Gunnison River by the East Portal. “That’s pretty incredible thinking about the people who built it so many years ago, with what technology did they have? A plumb bob and a ruler?” (And lots of dynamite.)

The Gunnison Tunnel is the critical link of the Wayne N. Aspinall Unit, one of the four projects that make up the 1956 Colorado River Storage Project. The Aspinall Unit, named after Colorado’s 24-year U.S. Rep. Wayne Aspinall, includes Blue Mesa Dam, Morrow Point Dam and Crystal Dam, all of which provide storage and generate electricity along a 40-mile stretch of the Gunnison River. 

The other units created under the 1956 Colorado River Storage Project Act include the Flaming Gorge Dam on the Green River in Utah, the Navajo Reservoir in New Mexico and Lake Powell in Utah. The network of reservoirs and dams are used by Upper Colorado River Basin states to store water and generate electricity as part of the Colorado River Compact that divides up the river between seven states and Mexico.

That venerable compact — the so-called Law of the River — is getting extra scrutiny now as a warming climate, reduced snowfall and increased demand stress the ability of the Colorado River to provide water to more than 40 million people. Farmers and ranchers, who use about 80 percent of the Colorado River’s water, are being asked to reduce their consumption while growing cities increase storage and weave conservation into their long-term planning. 

As a prolonged drought withers water supplies in the seven-state Colorado River Basin, deeper cuts in water allocations are looming. This summer the Bureau of Reclamation for the first time ever ordered the Upper Basin’s Flaming Gorge, Blue Mesa and Navajo reservoirs to send nearly 200,000 acre-feet down the Colorado River to Lake Powell so the Glen Canyon Dam could continue producing hydroelectricity through the winter. 

“Without it, there would hardly be anything here.”

The engineering masterpiece has sustained a lush vibrancy along the Uncompahgre River. It’s pretty simple to imagine what the valley would look like without that tunnel, says John Harold, who farms corn, onion and beans in the valley. 

“Just look at everything when you drive south out of Grand Junction. All desert,” says Harold, whose Tuxedo Corn Co. holds the patent on the Olathe Sweet variety of sweet corn planted on about 1,700 acres in the Uncompahgre Valley. “We get an average of 9 inches of rain a year, which isn’t enough to grow anything. Without this tunnel we would be a desert. If anything ever happens to that tunnel and that water went away, there’s no question this valley would return to a desert.” 

Agriculture consumes a lion’s share of the water that flows through the Gunnison Tunnel. But that share has dwindled in recent decades as municipalities grow and farmers fade in the drought. 

The importance of that tunnel beneath the mountains is not lost on residents in the valley. It is the region’s animating force, even as its economy grows and diversifies beyond a sole reliance on farming. 

“I’ve been looking forward to going down that hole for 70 years,” says Loren Dikeman, whose daughter works for the water users association and secured an invite for the annual trip into the tunnel once the water turns off for the season. “It took a lifetime to get it done.”

Dikeman’s family moved from the Eastern Plains in 1951 and started farming on about 160 acres. His trip through the tunnel was a chance to see the artery that pumps life into his hometown. 

“Everyone here really appreciates this tunnel,” Dikeman says. “How could they not. Without it, there hardly wouldn’t be anything here.”

Huddling in his rain jacket in the back of a rusty 1984 Chevy pickup as it bounces down the fetid channel, he laughs at the thought of a breakdown or a flat.

“Boy that would be a long, long walk in the dark,” he says.