Utah's soil moisture levels jump to 'uncharted territory.' Here's why that matters
by Carter Williams ksl · KSL.comKEY TAKEAWAYS
- Utah's soil moisture levels are now nearly 78% saturation, an unprecedented record for fall.
- Experts warn high moisture could factor into future flooding and other impacts.
- Utah's reservoirs have also received a bump; high soil moisture are likely to improve spring runoff.
SALT LAKE CITY — A storm system that pushed Utah over the weekend was mostly gone by Monday morning, but not before bumping statewide soil moisture levels to heights never recorded before.
"We're kind of in uncharted territory," said Jordan Clayton, a hydrologist for the Natural Resources Conservation Service and director of the Utah Snow Survey.
Utah's average soil moisture entered Monday at nearly 78% saturation, based on an average of three sensors at different ground levels at 144 sites scattered across various mountain elevations in the state.
For context, it's nearly four percentage points above the normal peak during the spring snowpack runoff, when soils are typically the wettest of any given water year.
Current soil moisture levels are approximately five percentage points above this past year's spring peak. They're only four percentage points below the highest point ever recorded since modern measurements began 20 years ago, when 2023's record-high snowpack melted.
The large spike follows what is expected to be one of Utah's wettest Octobers on record, and a strong start to November.
Some sites across Utah's Wasatch, Uinta, southwest and southeast mountain ranges received close to 10 inches of precipitation last month.
Overall, mountain precipitation last month landed in the 98th percentile, meaning very few years have been stronger, per the Conservation Service. Twenty Conservation Service sites netted their wettest October on record, while another 22 posted their second-wettest on record.
It's the first month of the water year, potentially setting the tone for 2027. The National Oceanic and Atmospheric Administration is expected to release its October report next week, offering a blend of mountain and valley data.
What's impressive is that levels are strong in every region.
"We're really seeing it statewide," Clayton told KSL, noting that every basin has "well above-normal" soil moisture levels.
The downside it has led to flash flooding, landslides and rockslides over the past few weeks, and those risks may continue with soil moisture levels that remain high.
It's a big reason that National Weather Service forecasters warned that flooding may redevelop near the Four Corners before the latest storm, and that's exactly what happened.
However, Utah's statewide reservoir levels have also jumped from 46% at the start of October to 49% to begin November. It seems small, but is impressive when they're set up to collect snowmelt.
Struggling bodies of water like Lake Powell and the Great Salt Lake have even received modest boosts for this time of the year.
Entering the unknown
Experts also know that higher soil moisture levels in the fall translate to more efficient snowpack runoffs in the spring, feeding the system that accounts for approximately 95% of the state's water supply.
Mountain soil moisture levels are essentially locked in place for the winter once the snowpack collection begins, which is partially starting now.
It isn't known if these high levels now may lead to issues reported in a water year like 1983, when the state's wettest fall on record, mixed with a then-record-high snowpack, led to widespread flooding and landslides across parts of the state in the spring of 1983.
Soil moisture levels weren't collected back then, but a late snowpack melt was a large factor in flooding back then, too, Clayton said. Thus, the impending snow collection season is also important in learning what happens when soil moisture is this wet in fall.
"What we don't know is how much this is going to benefit our snowmelt runoff because we haven't seen soil moisture conditions like this in Utah's mountains before," he said. "The snow has to come. It can't just be the moist soils."
Long-range models appear to favor moisture lingering through at least November, but higher probabilities of above-normal temperatures could factor into snow levels yet again. The National Weather Service Climate Prediction Center will release its final outlook for meteorological winter later this month.
The goal is to avoid bad soil-moisture years like last year.
Last year's soil moisture levels were also strong in the fall and winter, but Utah collected its worst snowpack on record, which led to poor inflows into the state's reservoirs.
The Key Takeaways for this article were generated with the assistance of large language models and reviewed by our editorial team. The article, itself, is solely human-written.