THISTLE — There's not much to see in Thistle nowadays.
Drivers heading toward Fairview through Spanish Fork Canyon can catch a glimpse of the ruins of a school and the remaining parts of a house surrounded by water.
All are remnants of the Utah County burg that drowned in the floods of 1983.
Utah high school seniors, who have known only drought-like conditions since entering high school, weren't alive when the earth couldn't hold all the water Mother Nature produced.
Today marks the 20th anniversary of the day that homes — and lives — in Thistle were torn loose from their foundations and swept away.
How it happened
Officials say several events caused the disaster, one of the largest mudslides in U.S. history.
First, the already-soggy soil in Spanish Fork Canyon simply couldn't continue to absorb water from the melting snow and the canyon's underground springs. As a result, dirt started moving downhill. In short order, the mud and rocks clogged the flow of a river.
A few miles south, heavy runoff was turning Thistle Creek into a raging torrent.
Water gushing out of Dry Creek Canyon tore across U-89, ripping out asphalt.
The fast-moving waters of Soldier Creek and Thistle Creek converged into the Spanish Fork River, which started to drown rural Thistle behind the massive slide.
The flood threatened to flow over the natural dam as the water rose. If that had happened, tons of debris-laden water would have spilled into Spanish Fork 11 miles away.
"The biggest concern was for the safety of people downstream," recalls John Mendenhall, whose father, Lynn Mendenhall, was the Spanish Fork river commissioner in 1983.
'Clinging together'
Renea Swenson still lives at her ranch near the slide area. Swenson recalls events surrounding the slide as if it were yesterday.
The Swenson family bridge was one of several that fell as water started to pool and rise.
Dale Barney, now the mayor of Spanish Fork, remembers returning from an 18-hour day working on flood-damaged areas to find the Spanish Fork River eating away at his feed lot.
"It was breaking off and falling into the river 10 to 15 feet at a time," he said.
Barney went to work placing logs and rocks to shore up the banks.
People turned out in droves to help Thistle residents flee homes and free livestock as the floodwaters rose. Cut off from the Wasatch Front, folks from Thistle and Birdseye were forced to drive to Manti, then cut through the mountains to Nephi, then to Provo along I-15.
The trip was more than 180 miles.
A narrow dirt road was carved out of the hills connecting Birdseye to Diamond Fork and then to U.S. 6 to Spanish Fork. It offered a shortcut for those brave enough to take it.
"It was a challenge," Swenson said. "Sometimes it was impassable."
Those who made the trip would bring back supplies for others.
"The beautiful part was the closeness and how we all worked together," Swenson said. "It was a time we were all clinging together for support."
The mudslide's toll
Within a week, water behind the mudslide had filled the canyon 200 feet above ground level. The water rose at a rate of more than 20 feet a day.
The town of Thistle became Thistle Lake.
Crews worked to open the highway and railroad tracks. The mudslide covered part of the Spanish Fork tracks, which led to Salt Lake City and Denver, vital markets for coal-mining companies in central Utah. Railroads were the first to begin tunneling through the mountain.
The U.S. Army Corps of Engineers pumped floodwater while other crews dug a drain hole to keep the newly formed lake from cresting the dam. Tunnels connected to the dam were built to drain the water.
And to prevent a repeat of the disaster, crews moved dirt from the top of the slide to the bottom for stabilization.
In all, it's estimated that the disaster cost more than $200 million, mostly because of the price tag for new roads.
The aftermath
The slide still moves a little each year. Red flags of alarm were triggered when the dirt on the mountainside slid about 150 feet from 1997 to 1998, said Francis Ashland, who works with the Utah Geological Survey Association.
Three years ago, the wire fence of a Thistle-area gun range snapped when the soil shifted 9 feet. The geological group keeps tabs on the small but continuous slippage.
In addition, a branch of the U.S. Department of Agriculture is trying to reverse the environmental damage done by the mudslide and some land-use decisions made in the subsequent years.
When the lake was drained, mud that had buried Thistle and Soldier creeks forced the natural flow of the water to cut steep new channels.
That led to tremendous soil erosion, said Cindy Burton, a range conservationist with the Natural Resources and Conservation Service, an arm of the agriculture department.
Burton also gives irrigation tips to farmers so more sediment doesn't wash into the creeks and eventually the Spanish Fork River. Conservation experts also advocate re-routing streams and planting willows at the side of the streams to prevent erosion.
Don Wiley, a fish conservationist with Utah's Division of Wildlife Resources, said some of the stream beds came back without much human help.
As the streams heal, fish habitat improves and brown trout, the most common species in the creeks, are thriving.
"You can pull 18-inchers out of there," Burton said.
E-MAIL: rodger@desnews.com