My Views of Utah


Mother Nature Built a Dam

Photos taken June, 2001

(Information taken from the US Forest Service view site information kiosk and from personal recollections.)

Photos by Venita*

small map

Record breaking precipitation in Utah during the fall and winter of 1982 set the stage for what would be devastation for the small town of Thistle, located at the junction of Highways 6 and 89 in Spanish Fork Canyon. Unseasonably warm days in April 1983 caused quick snowmelt, saturating the soil and causing small landslides to accumulate at the top of an ancient landslide. By mid April the accumulation caused the whole mass to begin moving toward the bottom of the canyon.

Earliest indication of the impending land movement started with mud slipping down the hillside and onto the Rio Grande railroad tracks which ran along the south side of the Spanish Fork River. Maintenance crews, unable to keep the spills cleared, soon had the additional job of keeping the tracks aligned as the movement underneath continued. Across the river, Highway US 6/89 travelers started noticing cracks in the road which developed into large buckles, leading to the closure of the Highway. All the while, backhoes and caterpillars were being used around the clock in a massive effort to keep the Spanish Fork River channel open. With the wall of mud coming down at one point at 3.5 feet per hour, it was soon evident that this was a land movement of catastropic proportion.

Slide view from top

Above: This view from the US Forest Service view site at the top of the pass through Billy's Mountain reveals the size of the land movement. U.S. Geological Survey Post-disaster investigations revealed that the debris, a moderately plastic gravelly clay, slid on a trough-shaped depression in bedrock. The site has apparently been involved in repeated landslides and earthflow movement through historic and pre-historic time. However, there is good geoligic evidence that the 1983 land movement was unprecedented in at least the past several hundred years.

View from bottom of dam

Above: View from the original road level at the bottom of the canyon, just north of the Spanish Fork River. The dirt road in the photo was used by equipment working to stabalize the dam. In five days, Thistle Slide created a lake 2.5 miles long and 200 feet deep covering an estimated 900 acres. With the stability of the natural dam in question, it was decided to stabalize the dam and drain the lake. Construction of an upper spillway tunnel [upper left] was completed in May while water was being piped over the dam from a temporary barge on the lake. Later, a lower drainage tunnel was constructed to drain the rest of the lake (Dec. 1983). This tunnel is the current passage under the dam for the river.

View from old road

Above: View from the old canyon road alongside Spanish Fork River, now muddy with spring run off. Two Denver and Rio Grande railway lines were blocked as well as Highway 6 and 89. This view shows the two tunnels built through Billie's Mountain to re-route the rail lines, well above the previous river level location.

Old road, rail road, new road

Above: Originally, the river, canyon road and railroad all flowed around the south end of Billy's Mountain which presented a steep and forbidding climb. Because of "Thistle Lake," Billy's was confronted. The railroad tunnels through the mountain are seen at the right where the train has just exited on its way down the canyon from the Carbon County coalfields in eastern Utah to industries in Utah County and beyond. New Highway 6/89 rises on a steeper grade to the huge gash at the top. Just beyond this summit the highways divide with Highway 6 continuing east and Highway 89 turning south to Sanpete County and beyond.

Bottom: At the summit we see the angle of the man-made cut and various colors of the sand and sandstone that make up Billy's Mountain. The US Forest Service has provided a view site and information kiosk here for information about the landslip and for photo opportunities.

Summit over Billy's

Many people hoped "Thistle Lake" could remain and become another water recreation and fishing site. However, the experts determined that the dam was unstable and would probably fail someday and flood the towns between it and Utah Lake. Not only that, the lake was filled with all sorts of dangerous debris of all sizes, including buildings from the small town of Thistle that it had drowned.

All the Thistle residents were safely evacuated with the help of family, neighbors and volunteers, leaving behind their homes and flooded dreams. After the lake was drained, some residents returned to claim whatever they could and others never looked back. A few rebuilt and started over. Since 1984, Mother Nature has replanted much of the land with native grasses and sagebrush, but evidence of the disaster is still easily seen.

Let's go over the hill and see some remains of the flood.

*Unless otherwise noted, all photos on this website were taken by Venita, who also holds the copyright. Should you wish to download any of them for any reason (other than your own enjoyment), please credit  Venita  as the photographer and add my URL:

Comments are appreciated!

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