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SALT LAKE CITY — No, it's not your imagination, the water is flowing much faster through Salt Lake City's Tanner and Sugar House parks, and that trend will continue over the next few weeks.
Salt Lake City Public Utilities started releasing additional water from Little Dell Reservoir into Parleys Creek last month, but department officials told KSL.com that they started increasing those controlled releases from 40 cubic feet per second to 50 cubic feet per second on Tuesday.
The measure isn't uncommon, but it's meant to open space in the reservoir to account for an above-normal snowpack that has yet to melt, much like the agency did ahead of last year's record snowpack.
"Our reservoirs are fuller, so water managers are really working on making sure there's room in reservoirs to provide an operational flood control purpose," said Laura Briefer, the department's director. "The biggest concern now is pivoting from managing flood risk after several years of drought to managing flood risk when we have fuller reservoirs."
Balancing capacity
Little Dell Reservoir opened in 1993 to create additional water supply for Salt Lake City, but it also serves as an important flood control measure. It was designed to back up Mountain Dell Reservoir in the wake of record flooding in 1983 that ravaged Salt Lake City following one of its strongest snowpack years ever.
It's currently the only reservoir collecting water in the canyon because Mountain Dell Reservoir is being renovated.
It was listed as having about 14,600 acre-feet of water on Tuesday, short of its capacity of a little more than 20,500 acre-feet. However, per Natural Resources Conservation Services data, the Parleys snowpack basin is now up to 27.1 inches of snow water equivalent after a storm this past weekend, 131% of its seasonal median average.
Thursday marks the area's normal snowpack collection peak.
Briefer said the above-normal snowpack is expected to send 6,700 acre-feet of water toward Little Dell Reservoir in the coming weeks as the snow melts. The department is conducting controlled releases to balance the difference between the amount left in the snowpack and the reservoir's available capacity.
Tuesday's increase addresses an estimated 1,000 acre-feet of extra water generated from storms that slammed the region over the past few weeks.
"We'll be doing controlled releases until we feel comfortable that we have adequate storage in Little Dell to store the water that will be running off," she said. "It's a little bit of a moving target because we look at conditions on a day-to-day basis to try and estimate how long we'll be releasing. It's going to depend on the weather."
A 2023 repeat?
The city conducted a similar measure last year when Salt Lake County — and the state — collected the highest amount of snowpack on record. In addition to controlled releases out of Parleys Canyon, the city also cleared branches and other items that could block streams and rivers over flooding fears.
The Sugar House Park's pond also served as a retention reservoir, holding more Parleys Creek water before it reached other parts west of the city. The city avoided a 1983 repeat, aside from one big incident. A clogged culvert led to a voluntary evacuation of 40 homes near Emigration Creek last April.
A mild and somewhat stormy spring ultimately spared Salt Lake City and Utah from the worst flooding fears, creating an efficient way for the record snowpack to flow into reservoirs. Briefer said the whole experience helped the city "test the system" so that it's prepared for the worst case scenario, but also she's hopeful that this year will produce an equally gradual snowmelt.
"We want that variation in our spring weather rather than it just becoming hot all of a sudden and lasting for a longer period of time," she said. "We want that heating and cooling to happen in a very gradual way."
Long-term forecasts lean in Utah's favor in this regard. The National Weather Service Climate Prediction Center's forecast lists Utah as having "equal chances" of above, below or near normal temperatures in April and over the next three months combined. It leans toward more precipitation this month, but it's unclear beyond that.
This indicates that trends are leaning toward a mixture of warmups and stormy cooldowns which can create a more measured snowmelt, says KSL meteorologist Matt Johnson.
"Ideally, we just get intermittent storms," he said. "We need the high-pressure systems because we need to melt off some of the snowpack, but we don't want it to come down at a fast rate."
Faster stream flows
What also helps is that this year's snowpack, while above normal, is nowhere near last year's record. The Parleys basin, as of Tuesday, remains 13.8 inches below where it was this time last year and 17.4 inches below last year's record peak. And since this year's winter was warmer than last year's, there's less snow in mid- and low-level snowpack basins in other parts of the city.
On top of controlling releases at Parleys Creek, City, Emigration and Red Butte creeks are all projected to peak at different times over the next two months and below flood stages, barring a major warmup melting the snow all at once, Briefer said. That would allow the city to focus on each creek as they reach peak flows.
Meanwhile, the city has been diverting the Jordan River's high flows — created by controlled releases from Utah Lake — into a surplus canal that begins in Glendale so the river doesn't overflow in the city. These bodies of water also flow into the Great Salt Lake, which has plenty of space to collect the additional water as the state tries to get it back to a healthy water level.
This is why Briefer is hopeful the city could avoid severe flooding again this year. That said, she points out that residents should still be cautious around all the rivers and creeks throughout the snowmelt process.
"(People should) be very careful with pets and children around these streams," she said. "They are flowing faster and deeper than normal."
