When people installed irrigation systems in Twin Falls, they didn’t expect the dry land to turn into a swamp. To solve this problem, the tunnel was built.
TWIN FALLS, Idaho — In 1894, Congress passed the Cary Act, which gave each state one million acres of desert land if it could be irrigated and cultivated within ten years.
“A lot of people would have gone bankrupt because a farm that you can’t work and build on isn’t worth anything,” said Brian Olmstead, a fourth-generation Twin Falls farmer.
Twin Falls was the perfect location for such an endeavor, when local entrepreneur IB Perrin and billionaire steel magnate Frank Boulle teamed up to harness water from the Snake River to provide water for their farmers.
Harnessing this seemingly limitless resource seemed to solve the big problem of how to populate the desert, but it actually created another problem that farmers were unable to solve for years.
That was the case 100 years ago, and most Twin Falls residents don’t realize that the solution to their problem still lies just 10 feet beneath their feet.
The Magic Valley is home to more than one million acres of irrigated farmland, and without water, Twin Falls, a mix of cropland and cul-de-sacs, would not look the way it does today.
But even then, that was hardly the case.
Olmsted, like many of his relatives, had lived in the area all his life, but there were still some things he didn’t know about his hometown.
We went down with him into one of the tunnels.
“So I’ve heard these legends about the tunnel my whole life,” Olmstead said, “and there are some places here that are kind of mind-blowing to me, but look closely. I never thought they were true until I worked for the canal company.”
He started working for the company 25 years ago, he explained as we waded through the water.
“There’d always been stories about vagabonds living there, murderers and all sorts of things,” he said. “The cave is about 2,000 feet long, just under a half mile.”
The tunnels weren’t created by chance, they were blasted into the lava… for a reason.
As we walk through the tunnel, Olmstead points out something.
“Do you see that? That’s a well that was dug to pump air into the tunnel,” he said.
To understand why, you have to go back to the time of his great-grandfather, who settled in the Magic Valley in 1904. Olmsted said they were buying a promise of water — and it wasn’t just a promise his relatives bought, it was a promise made to many others.
“It wasn’t called the Idaho Trail. There was water in Oregon, and they wanted to get out of here fast,” Olmstead said.
If that promise had been kept, Twin Falls would have had its water delivered in 1905. The completion of Milner Dam on the Snake River and the subsequent canal paved the way for the future irrigation of thousands of acres of farmland.
Jennifer Hills, a historian at the Twin Falls Public Library, said things changed quickly once irrigation was introduced.
“If you had been here in 1903 and then gone back in 1906, it would have been magical to see what was growing in the fields back then,” Hills said.
Local historian Jim Gentry said it will take years to resolve the problems caused by irrigation.
“Yes, by 1911 they knew they had a problem,” Gentry said. “I’m interested in how problems are dealt with in local history. The problem was there was too much water.”
How was that possible in a high desert landscape of lava and sagebush?
When farmers on the south side of the Snake River figured out how to irrigate their fields, they assumed that any water not absorbed by the crops would seep underground and eventually emerge through the porous walls of the canyon, just as it did on the north side. What they didn’t realize was that just four feet below the surface was a thick, extremely hard layer of lava rock.
“The water wasn’t draining and it wasn’t draining in a way that was expected, so it caused a big problem for them,” Gentry said.
Several months into the growing season, the water had no choice but to flow back.
“The pressure just kept building and building, and it was bubbling all over the place, from the lava into the soil,” Gentry says. “By 1911 the water table had risen so high that it turned farmland into a swamp.”
At the time, approximately 150,000 acres of land around Twin Falls was used for agriculture.
A small proportion of them had succumbed to flooding.
“By 1913, we had about 500 acres that were not tillable,” Gentry said. “Two hundred and five hundred acres doesn’t seem like a lot, but the acreage continued to grow.”
By digging ditches and wells, the Twin Falls Canal Company was able to reclaim several acres of land at a time, but they could not curb the drainage problem.
“Well, the problem is that we went from an area that seemed to have unlimited water in a good way to an area that has unlimited water in a bad way in terms of drainage,” Gentry said.
“Then in 1924, the canal company’s new general manager, Burton Smith, decided to take a different strategy with the land just above Rock Creek Canyon,” he said.
Smith asked the canal company’s board of directors for permission to dig a tunnel. He was denied, but he went ahead with it anyway. A dynamite explosion shook the city of Twin Falls. Soon, the repercussions of that dry run would finally pay off.
“When they started blasting up there, the ground above shifted and the water went right through,” Gentry said.
With water flowing through cracks in the rock and wells dug from the surface, the first tunnel would soon drain about 1,000 acres of farmland. 3.2 million gallons of water would flow into Rock Creek Canyon per day. The perfect solution to their problem was realized thanks to an experiment by a rebellious manager.
“I think they built eight tunnels within the next few years,” Gentry says. “This story is popular because it fits with a sense of Western individualism and freedom from bureaucracy. Without the tunnels, the land would be worthless.”
That’s the story of how these tunnels saved Twin Falls.
Fast forward to today, and my photographer, Kevin Esslinger, and I are in one of the tunnels with Olmsted.
The original tunnel was originally called the “Oar Tunnel” after the landowner above, but it came to be known as the “Fish Hatchery Tunnel” because the water coming out of it was a filtered 58 degrees – perfect conditions for the fish hatchery that was being built in Rock Creek Canyon below.
From there, dozens more tunnels were created and more expertly dug over the years to drain several other canyons, including Dry Creek, Dead Man’s Gulch, Cedar Draw in Filer and Mud Creek in Buhl. Olmsted said it takes about two months into the growing season for water to flow into the tunnels.
By fall, most tunnels are knee-deep in water, and in years with less water, some of that water can be resupplied to farmers to extend the growing season, he said.
Olmsted helped Gentry write his new book, “The 51 Tunnels that Saved Twin Falls.”
Inside the tunnel, Esslinger followed Olmsted to the end of the Fish Hatchery Tunnel, a total distance of 1,828 feet.
I didn’t – I prefer more open areas – but Esslinger left his camera about 300 feet from the entrance.
Ten minutes turned into 30, then 40 while we both explored. Eventually we escaped and I learned that maybe I should have chosen the right path.
Check out our YouTube playlist for the latest news from around the Treasure Valley and the Gem State.
Other ways to get news from KTVB include:
Download the KTVB News Mobile App
Apple iOS: Click here to download
Google Play: Click here to download
Watch news reports for free on YouTube: KTVB YouTube Channel
Live stream for free on ROKU: Add the channel through the ROKU store or by searching “KTVB”.
Stream Live for Free on FIRE TV: Search “KTVB” and click “Get” to download.
