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SALT LAKE CITY — "Significant" snowpack levels have prompted city and county officials to order a controlled release of water from reservoirs in Parleys Canyon on Tuesday, citing flood risks in the area.
Salt Lake County Flood Control and Salt Lake City Department of Public Utilities coordinated a release of 10 to 20 cubic feet per second of water from Little Dell and Mountain Dell reservoirs on Tuesday. Officials from the two agencies said Wednesday those will be increased to 50 to 60 cubic feet per second, and possibly higher this spring as a precautionary measure to prevent flooding.
"It is important for our teams to be proactive in anticipation of this year's high spring runoff," Laura Briefer, director of the Salt Lake City Department of Public Utilities, said in a statement.
Officials warn that it also means water will be moving much faster than usual in Parleys, Emigration, Mill, Red Butte and City creeks. Parleys Creek cuts through Tanner and Sugar House parks, which are popular areas for children and pets.
"We ask residents to please be careful around creeks and rivers," Kade Moncur, director of Salt Lake County Flood Control, said, adding that the water in the creeks will be cold and swift, which is why people should be careful and make sure their children or pets don't get too close to the water.
Due to significant snowpack SLCPU has started controlled water releases from Little Dell and Mountain Dell Reservoirs. Parleys Creek will be moving fast and the water is cold. Be careful around creeks and rivers. #floodcontrol#sugarhousepark#snowpack#wasatch#canyonpic.twitter.com/WUtGzwR2k2— SLC Department of Public Utilities (@SLCPU) March 1, 2023
Briefer explained to KSL.com that the two departments review snowpack levels and reservoir conditions every year. Little Dell Reservoir is currently at 12,900 acre-feet, or about 70% of its capacity before the snowpack runoff. Mountain Dell Reservoir is currently empty as it undergoes repairs, though the water from the other reservoir runs through a bypass set up in the canyon.
The reservoirs are within the Provo-Utah Lake-Jordan snowpack basin, which was listed as averaging 25.5 inches among its 19 sites Wednesday morning, according to Natural Resources Conservation Service data. That's almost 6 inches above the region's average snowpack collection over the past 30 years with over a month left in the normal snowpack collection season.
We want to make sure we have the ability to store water so we don't have flooding concerns in Salt Lake City.
–Laura Briefer, director of the Salt Lake City Department of Public Utilities
The snowpack runoff season is on the horizon, too, as Wednesday marks the start of meteorological spring. Projections estimate that the snowpack above the reservoirs will provide about 16,500 acre-feet, well beyond what's needed to refill Little Dell Reservoir — a reservoir completed in the 1990s to prevent flooding like the historic 1983 flood in the future.
"What we saw is that the amount of water that's likely in the snowpack exceeds the amount of capacity in the reservoir system," Briefer said. "We want to make sure we have the ability to store water so we don't have flooding concerns in Salt Lake City."
Utah Division of Water Resources experts told KSL.com last month that the perfect conditions are needed for an efficient flow. Laura Haskell, the division's drought coordinator, explained that flooding occurs when the snowpack melts too quickly, while it may end up going into the ground if it melts too slowly.
"There's this sort of perfect (scenario) where it melts a little then it sort of freezes overnight," she said. "A lot of it really is up to Mother Nature — how it melts and how much we get to see in the reservoirs."
While the measures at the two reservoirs are meant to control flood risks, they may provide an additional benefit. The five creeks ultimately empty out into the Jordan River, which dumps water into the Great Salt Lake.
State officials noted last week that the lake, which hit a record low again in 2022, has already gained 1½ feet since November.
Briefer said it's unclear how much more it will benefit the Great Salt Lake because the reservoir water may have ended up in the lake at some point anyway. But, nevertheless, the additional water from the reservoirs should help the lake continue to gain water this spring.
"Essentially, we're releasing water that will end up in the Great Salt Lake," she said. "Because we have a large snowpack this year, just in general, I think the Great Salt Lake will benefit from increased water in the system."