1983 was Utah’s great flood year, the year Salt Lake City’s Main Street briefly turned into a river. But Davis County was among the areas with the greatest destruction that year. Yes, because of the historic floods, but also because of the number of landslides and the sheer extent of the damage.
According to a 1989 report by the Utah Geological and Mineral Survey, more than 100 debris slides occurred in the county in May and June of that year, destroying homes and causing millions of dollars in damage.
Davis County is historically one of the most landslide-prone counties in the state, although Utah’s largest landslide occurred in Utah County near the Spanish Fork Canyon town of Thistle.
This spring was also wet, and the Utah Geological Survey estimates there have been 80 recorded landslides statewide this year, eight of which occurred in Davis County, according to UGS’s Greg McDonald.
Although the slides that year weren’t as damaging as they were in 1983, the increase in landslides may be related to that winter’s tremendous amount of snow, which, according to a Utah Geological Survey, results in saturated soils that can worsen during the spring runoff presentation prior to the Utah lawmakers earlier this month.
But given the high snowpack around Utah, there were fewer landslides this year than the UGS expected, according to McDonald.
“We knew there would be landslide problems due to record snowpack this year,” McDonald said. “There have been a few, and we’re still responding to several, but it’s not as widespread as it has been in years past.”
The 1983 landslides
Around Memorial Day in 1983, the cool, wet weather that had plagued Utah for months gave way to temperatures in the 1990s, leading to widespread flooding across the state.
The already wet mountain soil could not accommodate the record snowpack as the state had experienced severe winters for several years, increasing the risk of landslides and mudslides.
“The snowmelt just collapsed. “It just warmed up way too quickly,” McDonald said. “This caused a series of soils on the sides of these side canyons to become saturated and move into debris slides, which then became debris flows as they entered the flood channels.”
Among the hardest-hit areas was Farmington, where, according to the 1989 UGS report, a landslide pierced nearby Rudd Canyon, scattering earth and debris over nearly 18 acres of land. The landslide caused $3 million in damage to homes alone, as eight homes were leveled and 35 others damaged. The slide also caused over $1 million in damage to public facilities.
A May 1983 United Press International article described the Rudd Canyon slide as “a 20-foot wall of mud” that forced the evacuation of Lagoon Amusement Park. Farmington’s construction manager told UPI that officials evacuated the park “because of the large crowd there and we weren’t sure what the slide would do.”
In nearby Fruit Heights, 75 people were evacuated this spring after authorities began to worry about a landslide in Baer Canyon. The area avoided a large-scale disaster, but the report said: “Water pipes, culverts and personal property in this community were damaged.”
Bountiful also took a lot of damage. According to the 1989 report, two large landslides threw debris from the Stone and Barton creeks, causing approximately $4 million in damage. Water systems in Bountiful were contaminated after the aqueduct that carried irrigation water to the city was destroyed.
Overall, the report states that Davis County suffered approximately $18 million in damage from landslides in the spring of 1983.
years in between
Even without the record snow that triggered the 1983 landslides, Davis County has suffered landslide damage throughout the years.
In 1998, a landslide along Sunset Drive in Layton damaged seven properties and resulted in one home being demolished, according to a report by the UGS. City officials studied the risk of landslides in the area and later proposed building a drainage system near the ridgeline where the homes on Sunset Drive stood. However, according to another UGS report, “The majority of homeowners chose not to finance the installation.”
On April 15, 2006, the same chute was reactivated. As in 1983, the landslide could be associated with increased groundwater levels from snowfall.
“A 4 to 8 foot rise in groundwater levels between March 16 and April 17, 2006 appears to have triggered landslide action and is in part a result of the heavy snow and rain that fell on April 6,” the statement said UGS report Landslide on Sunset Drive, it said.
Layton assistant city manager Steve Garside said the Sunset Drive landslide was partly due to homeowner mistakes — a homeowner dug up part of his land to set up an in-ground trampoline for his children.
“When you pull the dirt off the sloping side of your foundation so there’s nothing holding the foundation back, that creates a small problem,” Garside said.
If you go to the 1800 block of East Sunset Drive these days, you will see two empty lots. The house that once stood at 1843 East Sunset Drive is no longer there: During the 2006 landslide, the house stood right on the embankment—or the edge of a landslide. Since the foundation was severely damaged, the house had to be demolished.
Southwest of Sunset Drive is another area of Layton where homes once stood.
According to a UGS report, six homes were hit by a landslide along Heather Drive in August 2001, causing over $1 million in damage and necessitating evacuations. Heather Drive is on a slope above South Fork Kays Creek.
According to the same report, the slide on Heather Drive happened slowly over several years. A homeowner noticed cracks in the foundation of his home in 1998. Another homeowner was repairing a driveway in July 2000 and noticed the floor was slowly moving for a year.
In August, houses on the north side of the road slowly slid off the road, leaving a several-foot gap between Heather Drive and the sinking houses. The chute also damaged buried water and gas lines, which were shut off while homes above creaked and bounced off the slow-moving chute, the UGS report said.
Three houses were removed by the landslide, and three others were demolished.
Layton Deputy City Manager Steve Garside said the homes lost in the Heather Drive landslide had been there for years, making the slide all the more surprising when it happened.
“(These houses) were actually built when the city of East Layton existed and East Layton became part of Layton City in 1981, so obviously these houses had been there for a long time,” Garside told The Tribune.
Months before the 2006 Sunset Drive slide in Layton, a child in South Weber was injured when a fast-moving landslide struck the back of a home and then broke through a wall, a UGS report said. There was a pond in a gravel pit at the top of the cliff where the slide began, and officials determined that the saturation of the cliff with water was one of the main reasons the slide formed.
Garside said Layton continues to make improvements to reduce the risk of landslides. Things like debris pools near the mouths of ravines can reduce potential damage when boulders flow through mountain streams.
“We always know Mother Nature wins, as we say, so the best thing we’ve done is make sure our stormwater drainage system can handle what’s out there,” he said.
But even with containment, landslides are still largely unpredictable. Last month, a Layton home on Hidden Hollow Drive was evacuated after a resident heard water running under the sidewalk. Over the next few weeks, soil shifted into the home, and UGS says two other homes may be at risk from the same slide.
In east Layton, another landslide occurred near Hobbs Creek Drive that same month. According to a UGS report, no buildings were damaged despite the slide, but the bottom of the slide appears to be near a house.
A landslide in Fruit Heights last month destroyed a building and injured two people. The razed building was not a residence, and according to a UGS report, the landslide was stable, although it could potentially move again with enough rainfall.
Like floods, landslides depend on the weather
Garside said the risk of landslides in the area depends in part on the weather, as with flooding. The sudden runoff triggered the 1983 floods and landslides, and a similar temperature swing would be potentially damaging.
According to Garside, Layton City were initially concerned about the snow at mid-levels, but in recent weeks much of the snow has melted. But not much snow has melted around Layton yet.
I’m “not excited about the 80s just yet,” Garside said, “but if we keep the 80s low into the 70s, we should be in good shape.” And I don’t expect any more slides.” He added Added the caveat that further landslides are possible if heavy rains are forecast.
But even with the region’s recent temperature shift into the high 70s and low 80s, a jump to hot weather doesn’t seem on the cards, at least for now.
McDonald said this year has been a fluke, as some UGS-expected declines held firm while other areas thought to be more stable eased. McDonald said the drought of the past three years and lack of groundwater could play a role, but there’s no way to be sure.
“It’s been a busy spring, but it wasn’t as bad as it could have been,” McDonald said.