Coloradans didn't use their sprinklers much in May. Here’s how much it helped.

Because Coloradans must always worry about too much or too little water, a wet spring would usually bring cautions about thriving underbrush fueling July wildfires, or May rains prompting flood warnings.

This is not one of those stories.

Instead, we come to quantify and celebrate a May of extraordinary rain that kept many Front Range sprinklers in the "off" position, and topped out reservoirs thirsty from drought.

Denver Water is ready with the receipts. May of 2022 had a 14-day stretch without rain for the state's largest water department, serving a quarter of the state at 1.5 million customers, while the longest stretch this May was five days without rain.

9News meteorologist Chris Bianchi added it all up on his Twitter account, noting that Denver enjoyed 5.53 inches of rain in May, compared with an average of 2.16 inches for the month. That was the fourth-highest May total on record, and the 11th wettest of any month on record, for an astonishing 40% of expected annual precipitation, Bianchi said.

This was Denver's:🌧️ Wettest month in nearly 10 years (Sept. 2013)🌧️ 11th-wettest month on record🌧️ 4th-wettest May🌧️ ~40% of our average annual precipitation#9wx #COwx pic.twitter.com/4DC4LzO7GJ

Demand in Denver was only 89% of a typical May, Denver Water spokesperson Todd Hartman said. The variable, of course, is lawn watering and when people turn on sprinklers in earnest for the season, since showers, dishes and bathroom breaks stay fairly steady.

That meant average demand for Denver Water this May was 169 million gallons a day. Last year, when May was hotter and drier than average, Denver Water was sending out 223 million gallons a day, or 143% of normal demand.

Natural watering played out this May across most of the state, from Aurora to Aspen, and Pueblo to Thornton.

The longest stretch of days without rain this May.

The demand of water last month compared to a typical May.

The demand of water May 2022 compared to a typical May.

"This is a good water year for Thornton, from both a supply standpoint and a demand standpoint," Emily Hunt, deputy infrastructure director for water at the city of Thornton, said in an email to The Colorado Sun.

Similar to Denver, Thornton has seen delayed irrigation lower its year-to-date demand about 10% from a normal precipitation year.

"This helps keep more water in our reservoirs, which will help later this summer when irrigation demands peak," Hunt said. " It may also help us go into the winter with slightly higher-than-normal storage levels, which is always a good thing."

Thornton currently gets its water from Clear Creek and the South Platte River, with additional rights to Cache la Poudre River water that it hopes to deliver through a long-delayed pipeline. Snowpack in the South Platte and Clear Creek basins was actually average to slightly below average, Hunt said, less spectacular than the dumps experienced by southwestern Colorado.

"But average snowpack is good for Thornton because we have senior water rights and sufficient storage," Hunt said, and spring rains delay residential irrigation and keep reservoirs fuller for longer.

In summer months, 75% of Thornton's water is going to lawn and landscape irrigation, Hunt said. Over the full year, that portion drops to about half of home water use. Thornton's peak day in 2022 was 46 million gallons delivered Aug. 5.

For those keeping score at home, May 11 was the big day for many Colorado water systems this year. Colorado Springs Utilities, which supplies water to much of El Paso County's large population, calls that storm a "deluge." Later in an email, they called it "torrential."

From May 11 to May 14, Colorado Springs residents consumed 53 million gallons of water a day, well down from the usual May average of up to 70 million gallons a day, spokesperson Jennifer Jordan said.

Steady melting of a healthy snowpack combined with the big May rains to bolster reservoir health for Colorado Springs, Jordan said.

"Our three reservoirs on the north slope of Pikes Peak gained a combined 42.5 acre-feet of water as a direct result of the May 11 storm, while our two Rampart Range reservoirs gained about 5 acre-feet from the event. The city of Colorado Springs received more than 3 inches of rain, but much of the precipitation over our local mountain watersheds fell as snow, which is now melting," she said.

One acre-foot of water supports two families of four to five people for one year, according to the 2023 Colorado Water Plan.

Count Aurora Water as very happy, but not throwing out its drought playbook. The big city system is staying on Stage I drought restrictions for now, meaning residential watering is only allowed on two days a week. Most Front Range water systems operating under normal conditions allow three days of watering a week.

That said, according to Aurora Manager of Water Conservation Timothy York, "we’ve seen a good response from many customers not turning on irrigation. The April and May precipitation certainly helped keep distribution down."

Use in Aurora has been running about 40 million gallons a day this year, which means the system has saved nearly 1,200 acre-feet of water compared with a normal year. Compared to the hot and dry early season of 2022, Aurora has used 2,200 fewer acre-feet, York said.

It's been an above-average snowpack year for Aspen, city utilities resource manager Steve Hunter said. That plus the wet and cold spring that is lasting until at least early June is a good sign for the city's water supply. "We’re cautiously optimistic. It's been a good year."

When May hits, Aspen ramps up to its peak season for water demand. Water use increases from 2 million gallons per day to 6 million to 8 million gallons per day — about 70% of that peak demand is from outdoor watering and irrigation.

Residential irrigation makes up the bulk of that water use, although some comes from commercial customers. The city is firing up ditches that carry untreated water to golf courses and small farms and ranches.

That increased water use is right on schedule in the high country this year, Hunter said.

"The lion's share is treated municipal water for outdoor irrigation for lawns and gardens," he said. "We see a big spike in that in the summer."

In early June, Hunter is going to recommend that the city council loosen, but not eliminate, water conservation restrictions.

The city has been in drought for four out of the past five years (2019 was the exception). They’ve been in the second-highest level of water conservation restrictions for the past two and a half years.

"It looks like we can reduce it (the restrictions) a little. Give people a break," Hunter said. "We don't want people just wasting water. … We have all these different water conservation things that are in place 24/7 during the irrigation season to help educate people."

Aspen, alongside other municipalities and organizations in the Roaring Fork Valley, is considering putting voluntary, year-round water efficiency and conservation standards in place.

"The caveat is that we may be coming back in a month or so and moving back in a more restrictive (stage) depending on what happens with weather and snowmelt conditions," Hunter said. "That's the big unknown — weather. Are we going to be wet and cool or are we going to be hot and dry? We don't know."

The reservoirs around Aspen are also looking good.

Nearby in Basalt, the federally owned Ruedi Reservoir is projected to reach its full capacity of about 102,000 acre-feet by the end of June or early July, Hunter said. Aspen relies completely on renewable energy, and the city has a 5-megawatt hydroelectric facility at the base of the dam. The city's hydroelectric power generation from the site is looking good with all the runoff, Hunter said.

Aspen's primary water storage reservoir — which Hunter likened to a small pond — is the Thomas Reservoir, which holds about 10 acre-feet of water. That's enough storage for a one-day supply during the summer when water is in peak demand.

As the spring runoff flows, that reservoir will be able to remain at capacity and isn't in danger of spilling.

"We have the ability to throttle the intake at Castle Creek so we never receive too much water," Hunter said.

"It's definitely a better year than it's been. It's also been a cold, wet spring so far. It looks like that's going to go into at least the first week of June, so that's good," Hunter said.

Fort Collins water watchers seem fairly sanguine as well at the beginning of their peak season.

"Our source water supplies come from the Cache la Poudre River and Colorado River basin," Fort Collins water conservation analyst Alice Conovitz said in an email. The city utility "benefited from the near-average snowpack in the Cache la Poudre River watershed, and from improving watershed health following the 2020 Cameron Peak wildfire."

As we said at the beginning, though, uncontained giddiness is not the nature of Colorado water watchdogs.

The rains in May fall mainly on the morose.

"If, in a week from now, it goes to sunny, blue skies and 85 degree temps … things could change in a heartbeat," Aspen's Hunter said.

Ditto Fort Collins:

"We are happy for ample snowpack and a wet spring this year, and we are still encouraging our customers to use water wisely, take advantage of conservation programs, and keep up good water conservation habits," Fort Collins’ Conovitz said.

Cue Aurora: "While all of these numbers are positive, the savings from early season delays in irrigation is a small piece of the overall picture as landscape needs are significantly less this time of year."

And finally, Denver asked explicitly if we’d include this caveat:

"While this May has been good for water supply, for reservoirs, for soil moisture and for lawns, we’d remind customers that things could dry out in a hurry and it's critical they maintain smart water and irrigation habits regardless of this short-term bounty," Hartman said.

"This is no time to rest on the laurels of a wet spring."

Michael Booth is a Colorado Sun reporter covering health, health policy and the environment.Email: [email protected] Twitter: @MBoothDenver More by Michael Booth

Shannon Mullane writes about Western water issues for The Colorado Sun and her work is funded by a grant from the Catena Foundation. She focuses on the Colorado River Basin, tribal affairs related to water, and West Slope water issues.Born in East Tennessee, Shannon has been in... More by Shannon Mullane