Mountain snowpack ‘looking good’ heading into spring

Big storms in February played a key role in boosting water supply.

April 6, 2020 | By: Jay Adams
Aerial picture of a frozen, snow covered Dillon Reservoir.
Dillon Reservoir in Summit County is expected to fill to capacity in late June or July due to above normal snowpack. Photo credit: Denver Water.


As Colorado copes with the impact of the COVID-19 pandemic, there is some reassuring news coming out of the mountains, where the snowpack is looking good heading into the runoff season.

Mountain snow, as it melts, fills Denver Water’s reservoirs, the main supply of water to 1.5 million people in Denver and several surrounding suburbs.

As of April 6, the snowpack in the Upper South Platte and Upper Colorado River basins, where Denver Water collects its water supply, stood at 115% and 116% respectively.

“Snowpack is looking good and we’re anticipating our reservoirs will fill when the snow starts to melt later this spring,” said Nathan Elder, water supply manager at Denver Water.

The snow season started strong with well-above normal snowfall in October. But while March is typically the snowiest month of the year, that was not the case this year.

River flowing in the middle with snow piled up around it and a forest behind it.
Snow piles up along the banks of Cucumber Gulch in Breckenridge on March 23, 2020. The snow will melt and flow into Dillon Reservoir. Photo credit: Denver Water.


“February was our biggest month across the central mountains so far this year,” Elder said. “About 30% of our total snowpack came from storms in February, that’s about double the average amount of precipitation for that month.”

Denver Water’s primary collection area includes the mountain peaks in Grand, Park and Summit counties, near the towns of Breckenridge, Fairplay and Winter Park.

Elder said the snowpack in those areas typically reaches its peak around April 23.

“April and May can still bring significant storms and the snowpack can change quickly,” Elder said. “But based on the last several months, we know this is going to be, overall, an above-normal snow year.”

Snow Water equivalent in South platte river collection system graphic.

Snow Water equivalent in South platte river collection system graphic.

Reservoir levels

As of April 6, Denver Water’s Dillon Reservoir was 90% full, according to Elder.

“We are fairly confident it will reach capacity this season, and that’s good news, since it’s Denver Water’s largest reservoir,” Elder said.

The utility’s other key reservoirs are Cheesman, near Deckers, and Gross, west of Boulder. As of April 6, those two reservoirs were at 70% and 48% of capacity, respectively.

Elder said both are likely to fill as well during the spring runoff.

Eagle statue in front of Dillon Reservoir.
An eagle statue in front of Dillon Reservoir in Summit County, where Denver Water collects and stores mountain snowpack. Photo credit: Denver Water.


Reservoir cycle

Denver Water relies on mountain snow for 80% of its water supply, with rain supplying the rest. When the snow melts, the water tumbles down rivers and streams that flow into reservoirs, where it is stored until needed in the metro area.

Reservoir levels, the gauge of how much water is in the reservoir, follow an annual cycle.

Levels drop to their lowest point around April 1, then begin to rise as the snow melts. The reservoir typically fills by July 1.

Then, as customers use water in the metro area, reservoir levels slowly drop through the summer, fall and winter months until melting snow once again fills the reservoirs the following spring.

River flowing with snow on the ground around it.
The Snake River in Keystone on Feb. 19, 2020. The river is a tributary of the Blue River, which flows into Dillon Reservoir in Summit County. Photo credit: Denver Water.


Computer models and projections

Each spring, Denver Water’s planners run computer models to project how much snowmelt will end up in the reservoirs in coming weeks.

These projections are critical, because the amount of water that’s available affects municipal and agricultural water supplies as well as recreation on rivers and reservoirs, fish habitat and the potential for flooding in communities located near rivers and streams.

The models use weather outlooks, streamflow forecasts, water rights and current reservoir storage levels. Streamflow forecasts are important because dry soil can absorb some moisture before it reaches mountain streams.

This year, despite snowpack being above normal at 115%, streamflow forecasts throughout the collections system are close to 100% of normal, which is another good sign that the reservoirs will fill in the spring.

Snow on the side of the mountain, with snowy mountain ridge in the background.
Snow from the west side of Loveland Pass is part of Denver Water’s Upper Colorado River collection area. Photo credit: Denver Water.


4 thoughts on “Mountain snowpack ‘looking good’ heading into spring”

  1. Question:
    Is the year round spring along Sunset Tr., Pine, Co. that runs into Elk Creek Denver Water? If so, at Jita and Sunset Tr. A culvert has been damaged. It has been bent for years but something happened to it recently. This creates a huge mosquito pond because the water does not continue to flow into Elk Creek.
    What can be done to solve this?

    1. Hi Shirley,
      We checked on that location in response to your query, and it’s not one that belongs to Denver Water. You may try reaching out to Jefferson County, as there’s a county road above the culvert.

  2. You should mention that water from the mountain streams in Summit County and Grand County on the west slope is diverted through tunnels to the metro area. These diversions have serious consequences for west slope streams on stream-dependent habitat, recreation, visual quality, and related functions. Denver Water over the past few years has entered into agreements and participated in collaborative efforts to restore the affected streams.

    1. Hi Timothy,

      Thank you for your interest in our snowpack story. You bring up a good point in explaining how water is diverted from the West Slope. Often in our stories we don’t put in the full details about how our collection system works in an effort to be concise and focused. We do have several stories that mention more details about our efforts to improve stream habitat due to water diversions and in this case, we could provide some links. Here are a few:
      Habitat resurrection means aquatic love connection
      Remodeling and restoring rivers — for trout and those who hook them
      A big water surge on the Colorado River
      Restored stretch of Fraser River opens for public fishing
      How a reservoir expansion helps rivers

      Thanks for reading and we appreciate your comments.

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