It seems no matter where you turn, Idaho is one exhilarating, awe-inspiring, and picturesque landscape after another. But if you’ve read any of our articles before, you know that our state’s history is just as fascinating as the beautiful landscapes we’ve all come to treasure. In fact, hidden beneath the surface of Idaho’s soil is a number of hidden surprises, sometimes in the form of our vast cave system – the product of our turbulent geologic history. Other times, these secrets are in the form of forgotten underwater ghost towns, left to decay in their watery graves. But did you know that there is an underground city of tunnels in Idaho?

Twin Falls is home to a surprising and unique underground city that few people know about but provides the very foundation upon which the Magic Valley thrives today. And it’s far more vast than you might expect.

Tucked away deep within Rock Creek Canyon, just south of Twin Falls, lies a forgotten remnant of the Magic Valley's origins, concealed by overgrown brush and poplar.
Dan R/AllTrails
An underground city of tunnels. And it's one of the most fascinating abandoned places in Idaho.
Magic Valley, Idaho canal tunnels
Irene Grassi/Flickr
Precious few people know of this underground city and even fewer have stepped foot inside the slick, waterlogged remnants.
Here, Klaar Tunnel - a name that is just as obscure as its history - acts as the entrance to an underground network of interweaving basalt caverns beneath the valley.
Magic Valley, Idaho canal tunnels
Andy/Andrew Fogg/Flickr
Klaar is just one of 49 tunnels that stretch for nearly 22 miles beneath Magic Valley, blasted decades ago in order to drain the region's water-saturated farmland. Most are about six feet in height and four feet wide.
The tunnels were intended to be the answer to the flooding concerns caused by the building of the Milner Dam in 1905.
Magic Valley, Idaho canal tunnels
elkbender257/Panoramio
With the Snake River diverted for irrigation, resident farmers quickly realized there was too much water coming in.

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They also discovered that southern Idaho's basalt rock isn't as porous as other types of rock, causing poor drainage and exacerbating the flooding situation. While the dry desert landscape flourished, the agricultural land became a sludge.
Magic Valley, Idaho canal tunnels
Allen Baxter/Flickr
The need for a solution was urgent. The water table was so high that farmers walking out to their fields were wading through mud that was calf-deep as water seeped up from beneath the soil.
Thus, these cavernous canal tunnels were dug for miles, anywhere between 30 and 40 feet below the surface of the town.
Magic Valley, Idaho canal tunnels
darkday/Flickr
Idaho's unique "city of tunnels" was blasted by the Twin Falls Canal Company in the early 1920s. The plan seemed simple enough: forge tunnels beneath the landscape and then drill vertical shafts to drain extra water directly into Rock Creek.
Nearly 350 men worked tirelessly on the tunnels, dozens of whom lost their lives to errant dynamite blasts.
Magic Valley, Idaho canal tunnels
Wikimedia Commons
A project of this scope had never been attempted before, Hundreds of square miles of farmland needed to be drained, and a special mining drill from Montana had to be shipped in to make headway. In 1951, the project was declared a success, dead-ending at a gushing underground waterfall.
Today, one can still hear the pouring water deep within the tunnels and see its eroding effects on the rock floors and walls. The ceilings are covered with mineral deposits from the constant trickling water seeping through the hundreds of drilled holes. Everything is preserved by nature and kept obscured from the public, sealed with concrete to protect the vital irrigation ecosystem.
Magic Valley, Idaho canal tunnels
stu mayhew/Flickr
Of course, in the first few years after the tunnels were completed, locals used these tunnels as shelter, for bootlegging, and as a base for other illegal acts. As a result, the entrances were blocked, concealed, and shrouded with time to prevent further activities, as well as for public safety. And for good reason: many of the tunnels lack breathable air and are easy to get lost in.
But while this city of tunnels may be long-forgotten and its precise entrance concealed, the very existence of these tunnels are a testament to the power of water in the state.
Magic Valley, Idaho canal tunnels
Jess Johnson/Flickr
They're also a sobering tribute to the lives of the workers who were lost in the process. Their efforts paved the way for the Magic Valley to flourish into the rich, geologic marvel that it is today.

Who knew there was an underground city of tunnels in Idaho? What other underground secrets are hiding in Idaho?

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Underground City Of Tunnels In Idaho

Melissa M. | January 02, 2022

What else is Magic Valley, Idaho known for?

Magic Valley is a region of Idaho known best for the Snake River Plain which had helped transform the area into a hub of agriculture long ago. Snake River Canyon is a big draw to the area and is home to the iconic Shoshone Falls as well as the Snake River. If you wish to explore the area on a hike, take the 12-mile paved Snake River Canyon Rim Trail which will lead you to some of the best views in the state. 

Can I visit any ghost towns in Idaho?

It’s almost hard to believe that there are around 100 ghost towns throughout the state of Idaho, and there are many you can visit. Mining was once a huge industry here, but when the industry tapered off, people left the mining towns. You can stop by Wickahoney, a ghost town in Owhyee County, where you’ll find a few buildings left to ruin. The town of Gilmore in Lemhi County was abandoned during the Great Depression and has several buildings that are somewhat intact. You can learn about several additional Idaho ghost towns in this post.

What are some of the most fascinating abandoned places in Idaho?

Aside from the underground city of tunnels mentioned above, Idaho has numerous abandoned places. One abandoned place that’s reportedly haunted is the Idaho State Reformatory, and you can spend the night…if you dare! You can learn more about spending the night at this haunted location in this article. If you desire a hike to an abandoned mine, you can do so along the Pulaski Tunnel Trail at the Panhandle National Forest in Wallace. The trail is only two miles and leads to an abandoned silver mine shaft. You can learn more from our previous coverage.

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