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Today in Weather History: Massive Mudslides in Utah

June 1983 saw some of the worst flooding that Utah has ever seen, with the damage estimated to be over $200 million.  When you account for inflation, that equals about $5.1 million today, with roads and railways becoming rivers and towns stuck in the mud.

Why Did the Flooding Happen?

Flooding in May and June often happens in states that often experience an increase in water levels due to summer coming. Snowpacks on mountain tops melt as the days heat up and become longer, causing the runoff to flow down the mountains and into towns. Utah has always prepared for this, but 1983 was different.

Perfect conditions, including a slow start to spring and heavy snowfall the winter behind it, led to very high levels of snowpack that had not started melting early enough. If it was a particularly warm spring that year, it is possible the melt could have been more spread it, leading to wet but not dangerous conditions. Instead, it snowed in the spring, adding to the trouble.

June saw rainy weather that did not help anything. Adding more wet to the already melting snow meant that streets were quickly flooding, despite the city’s best effort to sandbag roads and prevent damage.

So What Happened on June 12, 1983?

Streets in downtown Salt Lake City were sandbagged to help slow the flow of water into businesses and homes, but it did not help. Main roads were turned into rivers to direct the major flood of water away from populated areas.

The town of Thistle, Utah was completely overwhelmed as mudslides from the snowpack melt and rain created a natural dam, leaving the water nowhere else to go but sit and gather. Known as the “Thistle Mudslide”, this damaging mudslide actually destroyed the whole town.

Thistle, Utah

Thistle was a small town in Utah that got the brunt of this damage. The mudslide from the mountains dammed the Spanish Fork River and completely cut residents and rescue efforts off via the rail line that connects Salt Lake and Denver.

The movement of the mountain was first noted on these tracks, as they shifted while the earth was so soft and mailable underneath them. In the coming days, the tracks moved more and more, until they finally buckled under the pressure and were unpassable.

Residents were soon after asked to evacuate the area, and a mudslide of impressive size followed. Homes and businesses were destroyed, and residents never did return to Thistle, which remains as a ‘ghost town’ with few buildings still standing after their damage and subsequent abandonment.

This event, and the flooding, in general, that month, remains as the worst natural disaster in the state’s history.

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