- Lake Powell is projected to have its fifth-lowest runoff, at 36% of normal.
- Great Salt Lake tributaries may see bottom 10 runoffs, warns National Weather Service.
- Record-high temperatures and rain instead of snow affect Utah's snowpack and runoff.
SALT LAKE CITY — Last month's precipitation improved Utah's water outlook somewhat, but Lake Powell's and Great Salt Lake's tributaries are still on pace to produce some of their worst spring runoffs in history.
In fact, Lake Powell is currently on pace for its fifth-worst runoff on record, according to new projections released by the National Weather Service's Colorado Basin Forecast Center on Friday. The agency doesn't provide a similar comparison for the Great Salt Lake, but it warns that spring snowmelt runoffs could flirt with the bottom 10 runoffs in the many decades of tracking the Bear, Provo and Weber river basins, as well as Big Cottonwood Creek.
"Snowmelt runoff forecasts for Utah range from 21% to 83% of average," added Jordan Clayton, a hydrologist for the Natural Resources Conservation Service, in a water supply outlook the agency also issued on Friday.
The agency recommends that water users consider lower runoff given the high risk that spring conditions will be poor, he added.
A poor outlook
The Colorado Basin Forecast Center now projects that Lake Powell will receive about 2.3 million acre-feet of water this spring, which would be 36% of normal. That's not ideal, considering that the nation's second-largest reservoir — located along the Utah-Arizona border — is currently just 25% full.
There's also some variation in that projection. A warmer and drier spring, which is projected across most of the basin, could plummet its inflows closer to the record-low 963,000 acre-feet recorded in 2002, said Cody Moser, a hydrologist for the center.
"If we get 2002 temperature and precipitation now through the end of July, that would result in a volume that's less than what was observed in 2002," he said.
Members of the Colorado River Authority of Utah said last month that Upper Basin states will prioritize the reservoir's health this year, despite failing to reach a long-term agreement over its management with Lower Basin states.
National Park Service and Utah recreation officials are working on temporary and long-term ramp solutions to maintain recreation access, too.
Flaming Gorge, which is 80% full, is in a better spot, but its inflows might be only 64% of normal this year. Emergency releases from Flaming Gorge and other reservoirs in the Upper Basin are an option to temporarily boost Lake Powell, Gene Shawcroft, chairman of the Colorado River Authority of Utah, said last month.
Conditions closer to the Great Salt Lake aren't much better. The Bear River's projected snowpack runoff improved by about 15 percentage points from what the center projected in February, but it still expects that flows will be between 58% and 62% of normal across the Bear, Weber and Provo rivers, and Big Cottonwood Creek.
As such, the lake may not increase more than its current state or it could increase an extra foot, depending on different variables, including upstream diversions, Clayton wrote on Friday.
Snowpack runoff is still on track to end up below 50% in other parts of Utah, including the Virgin and Sevier rivers.
Utah leaders are monitoring the situation before issuing any declarations or measures, said Gov. Spencer Cox.
"The good news is we've been cautious. People have used less water," he told KSL on Friday, adding that Utah's reservoir levels are higher than normal, partially because of that. "We'll watch it closely. And if things dry out again, we may have to take steps earlier in the year than we normally would."
What went wrong?
The issue remains with record-high temperatures that persisted across the Colorado River and Great Basin throughout meteorological winter. Record-warm temperatures were observed across many parts of the Upper Colorado River Basin despite above-normal precipitation in some areas, resulting in poor snowpack accumulation.
Utah's statewide snowpack entered meteorological spring this week with 7.5 inches of snow water equivalent, 0.1 inches off the previous March 1 record since the modern era of snowpack data began in the 1980s, per Conservation Service data. Over a quarter of its sites reported record-low or near record-low levels.
Now at 8.2 inches, it's still at risk of becoming the state's worst peak on record.
A similar situation has played out throughout the region. Many low- and mid-level snowpack sites received rain instead of snow this winter, which improved soil moisture levels — a key component in snowpack runoff efficiency — but that doesn't help projected inflows to streams, creeks and rivers, Moser said.
"We are losing the snowpack and getting rain instead of snow," he said. "You really don't want to see these types of soil moisture conditions — above average prior to the April-July runoff season."
Despite some modest snowpack gains in February, snowpack levels above Lake Powell were only 52% of normal, five percentage points higher than at the start of February. The Upper Colorado Basin entered spring with the lowest snow cover since the Conservation Service began measuring it in 2001.
Other factors
The new outlooks are based on current conditions and the 30-year normal (1991 through 2020) for the remainder of the snow season, Moser said. That means there's still room for better or worse conditions, depending on how meteorological spring plays out — such as the 2002 scenario for Lake Powell.
March's robust start helps, but warmer and drier conditions are expected over the next week or two, which could speed up snowmelt. That would hurt the final outcome.
Some regions might be worse off than others. The Bear and Price watersheds could still end up with normal water supply conditions, but others aren't as likely, Clayton wrote.
"Particularly concerning is the potential for exceptionally low surface water supply conditions (relative to normal) in the San Pitch, Sevier and Beaver basins, as well as the majority of eastern and southeastern Utah," he added.
