With record snowpack, where will it flood in Utah?

Water districts around Utah are preparing for a heavy spring runoff in the coming weeks, all while southern Utah is already facing potential flooding.

(Francisco Kjolseth | The Salt Lake Tribune) Snowpack is high in the mountains as shown in Park City on Thursday, March 16, 2023. Authorities believe the heavy spring runoff will take place in the coming weeks and could cause floods across Utah.

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Water managers around the state are keeping a close eye on potential flooding but aren’t necessarily worried about the current status of the spring runoff.

At least for now — that could change with rain and snow in the forecast throughout the state this week.

[Related: Salt Lake City’s flooding in 1983 followed a year of rain and snow. Here’s what this year’s deep snowpack could mean.]

Most water managers have their focus set on mid-April when the spring runoff is expected to be much stronger, but it all comes down to whether or not the warmer spring temperatures happen gradually or all at once.

Flood watch in Southern Utah

Washington County, however, is the current exception. Much of the southeastern part of the state was under a flood watch last week because runoff from the melting snowpack was exacerbated by rainfall.

Jason Whipple, the county’s emergency services director, said, “When that happens, it all comes down at once. When it comes down with the heat, it still comes down, and it still comes down in a hurry, but not as fast and it’s a little bit more manageable.”

Parts of St. George — walking paths, golf courses and some roads — have already experienced flooding this season, and there is concern it will happen again as rivers rise. He said the county’s reservoirs are already at capacity and letting out as much water as possible to make room for the moisture coming down from the mountains and the sky.

Whipple also said emergency managers are keeping an eye on Brookside, an unincorporated community below Baker Reservoir, where some homes are built along the shores of the Santa Clara River. He said crews have already placed sandbags along State Route 18, which runs west of the town, and have removed debris from the rivers in the county.

(Mark Eddington | The Salt Lake Tribune) Gunlock Falls overflows the boundaries of the Gunlock Reservoir northwest of St. George, Monday, March 20, 2023.

They also have sent messages to community members warning of flood risk and are advising hikers to stay away from flood-prone areas where rushing water creates pop-up waterfalls.

“There’s a lot of things that are pretty to look at, especially the overflows and stuff like that, but they’re also unstable areas, so it’s dangerous,” Whipple said.

There also is a risk of flash flooding during storms and slot canyons — long, narrow channels with steep, sheer sides as the path runs through rock — can be particularly dangerous, since there’s normally no easy exit if water begins to rise. Zion National Park has closed one of its most popular hikes, a slot canyon trail known as The Narrows, because of fast-moving water. It will remain closed until the volume of water is under 150 cubic feet per second for 24 hours, according to its website. Last year, a 29-year-old Arizona woman was killed after she was swept away in a flash flood while hiking The Narrows.

At Gunlock State Park, spring runoff is sending torrents of fast-moving water over the state park’s red rock formations, creating roaring cascades and forcing the park to restrict public access as crews remove accumulated debris. Visitors can still see the falls — but at a distance, according to the park’s Facebook page.

Northern Utah’s runoff

One city in Box Elder County had its issues last week, with a handful of neighborhoods flooding after snow melted off nearby fields.

Paul Fulgham, public works director for Tremonton, said the snowmelt crept into neighborhoods in the afternoon of March 15 but had receded by noon the next day. He didn’t know of damages done to homes or water creeping into basements, but the brief flooding required sandbags to protect houses and pumps to drive out the water.

He said the Malad River was running above flood stage for much of last week before lowering Friday. Fulgham, who has been in Tremonton since the mid-80s, added it was the highest he has seen the Malad.

Last week’s runoff will likely be the only one this spring, with Fulgham saying, “the worst in our area is over with.” Though the Bear River runs near the town, often its flow can be controlled using Cutler Reservoir, Fulgham said. Tremonton will still have sandbags available for residents if needed, which can be picked up at the city offices or the city’s fire department.

Elsewhere in northern Utah, temperatures, for the most part, are still holding near freezing, meaning much of the mountain snow stays put, and the current runoff continues to be in its early stages.

“We haven’t had much (runoff) here,” Nathan Daugs, manager of the Cache Water District, said late last week. “We still got anywhere from a foot to a foot-and-a-half of snow on the ground, so most of our runoff is yet to come.”

To the south, the Weber Basin Water Conservancy District has already been releasing water from Wanship Dam as well as Echo, Pineview and East Canyon reservoirs in preparation for the runoff.

As of now, general manager Scott Paxman said he’s only worried about debris clogging up rivers. But he does anticipate flooding as the weeks drag on.

“My guess is we’re gonna see some typical flooding like we do up in Ogden Valley, on the North Fork — we’ll see some definitely on the lower Weber (River) and potentially up in the Oakley area, Kamas area.”

Hoping for a cool spring

(Francisco Kjolseth | The Salt Lake Tribune) Low water levels at Jordanelle State Park in September 2021. The reservoir is expected to fill up this year.

For the last six weeks, water managers at the Central Utah Conservancy District have kept the spring runoff under control by letting water out of one of its largest reservoirs — Starvation, a 3,500-acre lake fed by the Strawberry River in the desert west of Duchesne — to leave room for more water, said Jared Hansen, project manager at the Central Utah Water Conservancy District. But the upcoming storms are concerning, he said, because the rainfall could fill reservoirs beyond their capacity to release water.

“So as more storms come, then we need to think about how we’re going to manage that water out so we don’t constantly flood,” Hansen said.

For instance, until recently, Hansen said crews didn’t think Jordanelle — located above the Heber Valley and fed by the Provo River — would fill this year. After a recent storm, it’s clear it will.

Like in other parts of the state, he said crews have stocked sandbags and have scoured rivers for debris, like downed trees, that could clog flow and cause problems.

Hansen said he hopes for a slow warm-up to spring this year, like his water district saw in 2011, when the snowpack reached similarly high levels. If the weather stays cold too long and quickly shifts to hot for the summer, that’s when there could be widespread, catastrophic flooding — like crews saw in 1983.

Hansen said crews would monitor runoff and rainfall and adjust outflows from reservoirs “until the snow comes out.”

“It’s very dynamic right now. Somewhere’s gonna flood. … Somebody’s gonna get flooded. There’s record-breaking snow in some places, but at least the stuff we can manage, we’re pretty comfortable that we’ve got a good handle on it today.”

On Thursday, National Weather Service forecasters predict rainfall in valleys across the state that will switch to snow later in the day. They also predict “significant” mountain snow ahead of that rainfall.

“I may feel differently on Thursday,” he added, “but we will react. We’re not just going to sit and do nothing. We’ll be constantly adjusting until it’s gone.”

Hansen cautioned those recreating in rivers this spring to be wary of faster-than-normal flow and cold temperatures.

Shazelle Terry, assistant general manager for the Jordan Valley Water Conservancy District, said this spring has been colder than most, and mid-April will likely be the time frame where much of the spring runoff takes place.

“Currently, we’re still in pretty good shape,” Terry said Monday.

Officials in Salt Lake County are already gearing up for the spring runoff, with county leaders saying last week they anticipate large amounts of water to flow through Big and Little Cottonwood creeks.