The snow that piled up in Denver Water’s collection system brought good numbers and big surprises this spring.

The numbers were strong: A peak at 100% of average in the South Platte River Basin and a peak at 124% in the Colorado River Basin. 

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Those figures translate to a good snow year and a strong water supply for the warm months ahead.

The bigger surprise was how late into spring the snow stacked up. 

In the portion of the Colorado River Basin where Denver Water collects its water, peak didn’t hit until May 15 — three weeks after the typical April 24 high point for snowpack.

Such a late peak is good news for water supplies. 

Can you sing the summer watering rules? The Splashstreet Boys, with "I Water That Way."

It means higher streamflows in the warmer months and reduces wildfire risk, among many other benefits. It often means a boost for recreation, too, with more water available for rafting season and elevated reservoirs deeper into the summer.

“Most importantly, it means water availability coincides with water demand,” said Nathan Elder, Denver Water’s manager of supply. “We don’t see big water demands from our customers in April and May, so if the snowpack peaks later and runs off later in June and July, it keeps our reservoirs stable, sustaining our savings account, so to speak.”

This year, May packed a big punch, delivering a whopping 10% of the snowpack in the Colorado River Basin portion of Denver Water’s system. 

"That volume of May snowfall is rare,” Elder said. “We typically see snowpack losses in May and this year it gained."

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The season produced another quirk: snowpack peaked April 10 in Denver Water’s South Platte system, creating a 35-day stretch between peaks in the two basins. 

That kind of gap has only occurred once in 44 years of data. That was in 1983, when the peaks were separated by 36 days (April 15/May 21).

Know before you go: Check denverwater.org/Recreation for updates and information about recreation on Denver Water reservoirs. 

“This gap makes for a big deviation from the norm, which typically sees both basins hit peak within a couple of days of each other, in late April,” Elder said. “It’s another sign of how variable snowfall patterns can be in Colorado.”

Even so, both basins came in with strong snowpack numbers, bringing Denver Water a second straight year of healthy water supply.

The wealth of snow also means Denver Water will need to spill water from some of its reservoirs, an uncommon situation. The utility prefers to keep water in storage if it can, but a big runoff can force it to release water downstream to make room for more snowmelt coming off the high country.

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Strontia Springs, located about 6 miles up Waterton Canyon southwest of Denver, along with Cheesman Reservoir further up the South Platte, began spilling in mid-May.

The healthy winter also means average reservoir storage was at 88% in early May. 

That translates to a big splash of additional water — 35,000 acre-feet, greater than the capacity of Chatfield Reservoir south of Denver — above what is typically stored in Denver Water’s reservoirs at this point in the year.

Finally, a cool and wet spring have helped reduce customer demand for water. That, in turn, helps keep water in reservoirs and streams for later use.

“Our customers continue to watch the weather and be smart with their irrigation practices,” Elder said. “They play a big part in the water supply picture.”