How impactful have this year’s monsoons been for Utah’s water supply?

SALT LAKE CITY — Utah’s monsoon season is slowly winding down, but not before leaving an impact on Utah’s reservoirs in various ways.

No, the rain doesn’t boost Utah’s reservoirs quite like the snowpack and snowmelt process over winter and spring, but state water officials said Thursday that monsoonal moisture has major benefits that improve the state’s water situation.

First of all, cloud cover can reduce reservoir evaporation; however, Utah Division of Water Resources experts point out that any major downpour can also temporarily increase stream or river inflow into reservoirs, giving it a short-term boost. The rain can also improve the water quality in a reservoir by diluting pollutants and reducing sediment buildup, which also benefits aquatic habitats and ecosystems.

These can also reduce the need to consume water, either for farms, ranches or lawns, which is one of the primary benefits of the monsoon season because irrigation uses are a “significant draw on reservoir resources,” agency officials add.

The other major benefit is that they offer some drought relief. For instance, only 8% of Utah is currently listed in moderate drought and 26% is considered “abnormally dry,” as compared to 16.5% and 50%, respectively, at the start of August, before this year’s monsoons formed.

All parts of Utah were listed as being in at least moderate drought this time last year, including more than 95% in severe drought or worse.

Utah Gov. Spencer Cox also noted last month that monsoonal rain boosted the state’s soil moisture levels, which can improve the efficiency of next year’s snowpack runoff.

“Monsoonal moisture may not have been a silver bullet for our reservoirs, but it has been a lifeline in reducing demand,” said Candice Hasenyager, the director of the Division of Water Resources, in a statement. “It reminds us that nature plays an important role in our quest for resiliency, and reducing demand is the one lever we have to pull to secure our water future.”

The agency’s update comes after federal data showed that Utah experienced its 14th-wettest August on record, dating back to 1895. Last month was just one of 16 years where the state averaged more than 2 inches of rain during the month, according to the National Centers for Environmental Information.

The state’s fruitful 2023 water year and irrigation season are also both coming to an end in the coming weeks.

Some communities have already set records. For example, the National Weather Service confirmed on Monday that St. George broke its water year record, as it reached 15.79 inches.

Utah’s current water year is on pace to be the 17th-wettest on record with a statewide total of about 15.8 inches between Oct. 1, 2022, and Aug. 31, per the federal climate data. Most of that is tied to the state’s record snowpack, which reached 30 inches statewide for the first time on record.

Utah’s reservoirs are also in a much better situation than they were last year because of that snowpack collection and an efficient snowmelt process. The state’s collective reservoir system, excluding Lake Powell and Flaming Gorge, remains a little more than 75% full, according to the Utah Division of Water Resources.

Hasenyager said Thursday that this is the time of the year that Utahns should consider “dialing back” irrigation schedules and considering any remaining irrigation water use ahead of winter.

“As we transition into the next season, it’s important for everyone to be mindful of their irrigation practices,” she said. “Conservation is still a top priority in order to ensure responsible water usage.”