Vail Valley streamflows have peaked; summer could be dry
If the monsoon flows don't help boost streamflows, we could be in trouble this summer
- 0: Percentage of snow water equivalent at measurements stations on Vail Mountain and Copper Mountain.
- May 20: Melt-out date for the measurement site at Vail Mountain. The average melt-out date is June 4.
- June 2: Probable peak streamflow date on the Eagle River at Avon. The normal date is June 6.
- June 2: Probable peak streamflow date on the Eagle River below Gypsum.
While local streams are currently running fast and high, this season’s streamflow seems to have hit an early peak.
That peak has been driven in large part by an early melt-off of local snowpack.
According to data from the Eagle River Water & Sanitation District, Vail Mountain’s snowpack, as measured in snow water equivalent, melted off May 20, more than two weeks earlier than normal.
While the snowpack at Copper Mountain ran above the 30-year median this season, that site — the closest to the headwaters of Gore Creek — has also melted off. With the extra snow this year, that site melted off June 5. That site usually melts off by May 30.
There’s still snow on the Fremont Pass site — the closest site to the Eagle River’s headwaters. That site also had above-average snowfall over the winter.
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But a warm, dry April and May have accelerated the melt. The Fremont Pass site is on track to melt off before the average date of June 18.
Early streamflow peaks
Streamflows are also peaking early, and stronger than normal in some cases.
Gore Creek above Sandstone Creek peaked June 1 at 998 cubic feet per second. The usual peak of 792 cubic feet per second generally comes on June 5.
The Eagle River measurement site near the wastewater treatment plant at Avon also peaked at a higher than normal flow on June 2. The normal peak comes June 6.
The high-elevation snowfall received in the overnight hours between June 8 and 9 was good to have. Virtually all precipitation is a good thing.
But according to Eagle River Water & Sanitation District Communications and Public Affairs Manager Diane Johnson, that snowfall didn’t show any increases at the measurement sites.
With streamflows starting to subside, water supplies for the rest of the summer will need to be augmented by summer rain. Much of that rain usually comes from a monsoon atmospheric flow that draws moist air from the southwest.
Monsoon or non-soon?
Mike Charnick, a meteorologist at the Grand Junction office of the National Weather Service, said the monsoon can be “highly variable” when it comes, and how much moisture comes with it.
Charnick said the monsoons can come as early as mid-June or so. Most of the time the monsoons come in mid-July.
But that variability means sometimes the monsoons don’t come at all, particularly in this part of the state. The monsoons didn’t develop at all in 2018, a historic drought year. The systems also didn’t develop much in 2019.
The good news is that Charnick said a developing high pressure system should moderate some of the strong winds that have torn through the state in recent days. That wind has prevented moisture from absorbing into the ground, and taken surface moisture back into the air.
With dry, warm conditions the norm for the past couple of months, the water supply situation for the summer doesn’t look great right now.
The climate information arm of the National Oceanographic and Atmospheric Administration is predicting a chance of warmer than average temperatures, and an even chance of normal precipitation.
But June is traditionally a dry month in this area.
That’s going to impact both streamflows and water supplies.
Assistant State Climatologist Becky Bolinger of the Colorado Climate Center at Colorado State University wrote in an email that drought conditions “could persist or worsen until the start of the monsoon. If there is not a strong start to the monsoon or if it doesn’t extend far enough north this summer, western Colorado and the Four Corners could really be hurting by the (end of September).”
With a chance for above-average summer temperatures it’s likely the state’s drought conditions will worsen. At the moment, all of Eagle County is in either “abnormally dry” or “moderate drought” conditions. Most of the state is in some form of drought, with the southern part of the state the hardest-hit.
In the valley, that means residents need to be careful with water use, particularly outdoor water use. While almost all indoor use ends up being returned to streams, very little outdoor water use ends up back in the river. That can hurt streamflows and aquatic life.
“If you care about local streams … be as efficient as you can,” Johnson said.
Vail Daily Business Editor Scott Miller can be reached at email@example.com.