With snow leaving the spring stage, a look ahead at water supply
With the 2021-22 snow season winding down, Denver Water is getting a clearer look at water supplies approaching the irrigation, gardening and summer recreation season.
In fact, as 9News meteorologist Cory Reppenhagen has pointed out, much of Colorado likely hit its peak snowpack in late March, meaning we’ve started the process of spring runoff, when the snowpack begins to melt and flow into streams, rivers and reservoirs.
Watch Denver Water crews weigh the snow to find out how much water it contains.
In Denver Water’s collection system, which includes parts of the South Platte River and Colorado River basins, it’s not fully certain we’ve hit our peak — the point when snowpack reaches its highest point before melting off.
But we’re surely close, as snowpack in Denver Water’s collection system typically peaks around April 20.
What’s it all mean for our water supply? It’s a mixed picture.
Snowpack is a bit below average, but soil moisture has improved compared to last year, meaning more melting snow will find its way to reservoirs and less will disappear into thirsty ground.
Denver Water’s reservoirs are 79% full, on average, which is normal for this period. And runoff is likely to push that number north of 90% when storage peaks midsummer.
“Overall, we’d like the numbers to be higher, but with better soil moisture we expect better runoff than in recent years with similar snowpack,” said Nathan Elder, manager of water supply for Denver Water.
“We have good carry-over storage going into the runoff season because of low winter water use,” he added. “That’s a reflection of good work from our customers in continuing to improve indoor efficiency and water use habits.”
It’s important those good habits extend into the watering season; customers with spring fever should try not to get ahead of things with outdoor irrigation.
Learn how Denver Water works with ski areas through the winter.
Warning! April is too early to turn on hoses, sprinklers and irrigation systems.
A string of snowstorms this year has improved soil moisture in the Denver region. And more storms could still head our way in late April and early May. This time of year, the weather can be unpredictable, and you might think spring has sprung — only to have winter sweep back in for a last goodbye.
And planting ahead of Mother’s Day (May 8 this year) is always a gamble, as the potential overnight freezes still lurk into the early days of the month. Cold temperatures can put an early end to spring seedlings and damage irrigation systems if water inside the piping freezes.
As it stands in mid-April, snowpack is at 88% of average in Denver Water’s Colorado River collection system, and at 74% of average in its South Platte system, though that South Platte figure is affected by a single tracking location with poor snow that has pulled down the broader average; in the wider South Platte River basin, snowpack is currently 90% of normal.
And a big wet storm or two, still possible this time of year, would improve the outlook.
Additionally, planned Airborne Snow Observatories (ASO) flights, which measure high elevation snowpack with great precision, will bring additional insight into the snowpack, as well as adjustment to the runoff outlook.
In 2019, flights in the Blue River Basin above Dillon Reservoir revealed more snow than expected at elevations above traditional snow telemetry sites that provide most snowpack data.
“The ASO data gives us the most detailed and accurate insight into snowpack,” said Taylor Winchell, a climate change specialist at Denver Water. “We look forward to seeing what new information that tells us this spring and how it narrows the uncertainty of water supply forecasts.”
