Utah's reservoir system is quickly closing in on its mid-May average now that more than half of the state's record 30 inches of snowpack has melted.

The state's reservoir system, minus Flaming Gorge and Lake Powell, was back up to 65%, as of Monday morning, according to the Utah Division of Water Resources. In fact, more than 30 of the state's largest reservoirs in the state are listed at either 61% capacity or higher, including more than a dozen listed above 80%.

The capacity percentage is 2.9 percentage points below the average for May 15 but 7.5 percentage points above where it was at last year.

"We're in a much better place statewide with just a little less than half of our snowpack remaining," Candice Hasenyager, the division's director, told KSL.com. "We all hoped for a good year, and this year exceeded our expectations, hitting new records. ... This is much more than we expected and we're grateful for it."

State of the snowmelt

The state's reservoir system, not counting Flaming Gorge or Lake Powell, had fallen to 42% in November, about 12.6 percentage points below the average for the end of the year. The state withholds Flaming Gorge and Lake Powell from its statewide figure because those reservoirs don't supply much of the state's water needs, so it's a better assessment of the state's water supply.

The percentage began to recover because of the winter's record-setting snowfall. Utah's snowpack reached an average of 30 inches statewide in April, breaking the previous all-time record set in 1952.

Now all that snow is melting and the water within it is flowing into creeks, rivers and streams across the state. The statewide figure dropped to 50% of its peak on Saturday. As of noon Monday, about 16.5 inches of Utah's snowpack had melted since the second week of April, leaving 13.5 inches of snow water equivalent left in the mountains, according to Natural Resources Conservation Service data.

It's worth noting that 13.5 inches is still more snowpack than at any point during each of the last two snow collection seasons. It's also worth noting different parts of the state have had different snowmelt trends, Hasenyager explains. That means how much snow that is left to melt depends on where you live.

"Some areas of the state have a lot more snow than others — that statewide chart shows an average," she said.

For example, there are still 24.6 inches of snow water equivalent in the Raft River basin in northwest Utah, though most of that water doesn't impact the state's water supply. But there's also an average of about 20 inches remaining in the Weber-Ogden, Provo-Utah-Lake-Jordan and Bear snowpack basins that flow toward communities along the Wasatch Front and Cache valleys.

On the other hand, almost all of the snowpack collected in the southern Utah basins has melted since early April. About 92% of southeastern Utah's record 26-inch snowpack is gone, leaving it with 2.1 inches left to go, as of Monday. The five basins with the fewest snowpack left are all located in the south-central portion of the state.

How reservoirs are benefiting from the snowmelt

This is also why most of the southern Utah reservoirs are close to completely filled or are even exceeding full capacity at the moment. Many northern Utah reservoirs are also faring well at the moment because the snow that has melted already represents a normal snow year, even if it's the halfway point of what was collected this season.

In fact, a major reason many of the northern Utah reservoirs aren't full is that there's so much water in this year's snowpack that water managers have had to release stored water to avoid flooding concerns. The Weber Basin Water Conservancy District is the latest district to specifically release water out to the Great Salt Lake to help the struggling body of water while also lessening severe flood risks.

This map shows the water levels of Utah's reservoir system. The state's reservoir system, minus Flaming Gorge and Lake Powell, is back up to 65% capacity, as of Monday.
This map shows the water levels of Utah's reservoir system. The state's reservoir system, minus Flaming Gorge and Lake Powell, is back up to 65% capacity, as of Monday. | Utah Division of Water Resources

Hasenyager says her division believes most of the state's reservoirs will refill this year. That said, the balancing of what's left in the snowpack and controlled releases actually makes it difficult for the division to project exactly what Utah's reservoir capacity will look like by the end of the snowmelt, which could happen in June or July. So it's not really clear how high it will get beyond the current 65%.

"Water managers do have that tough job of making those daily decisions on how much to release and how much to store," she said. "Predicting the exact end-of-melt capacity is really challenging. It's dependent on ... unpredictable factors like weather and water usage."

Construction is another reason some other reservoirs aren't filling up right now. For example, Yuba Reservoir in central Utah is only 12% full because of an ongoing project to repair the dam in the area. Hasenyager said she expects those reservoirs to refill once the project is completed, which will also factor into the final capacity figure this summer.

Major reservoirs along the Colorado River Basin like Flaming Gorge, currently at 72% capacity, and Lake Powell, at 26% capacity, are expected to benefit this year, as well. The U.S. Bureau of Reclamation issued a report last month that estimated Lake Powell could rise anywhere from 50 to 90 feet, far from full capacity but easing back some hydrological concerns at the moment.

Meanwhile, Hasenyager said this winter shouldn't stop Utahns from making decisions to reduce the water they use, especially as this year's irrigation season begins. She points out that all the water people continue to save now will help create "breathing room" for the reservoirs, essentially prolonging the length of time a reservoir needs to be refilled the next time there is a severe drought.

"If we're not in a drought, we're preparing for the next one, so it's really important for people to stay water-wise and look for ways to reduce as much water we use," she said. "It's critically important for all of us — as water users and residents of the state, but also for the environment and the Great Salt Lake — to make water-wise decisions."