Thursday, May 09, 2019

Summit County will see a cooler, wetter spring, setting the stage for possible flooding

#Summit County #Colorado
Summit Daily

The 26th annual Summit County State of the River meeting took place at the Silverthorne Pavilion on Tuesday evening. The meeting, organized by the Colorado River District, drew together dozens of local, state and federal water officials, business leaders, ranchers, farmers and others with stakes or interest in the Colorado River, the lifeblood of the West.
The mood at this year’s State of the River was more upbeat than last, when a historically dry winter and hot summer led to increasing worries of a future water crisis. Major reservoirs had been struggling to make up for previous year shortages during a decadelong drought.
But thanks to one of the wettest, wildest winters in recent memory, Colorado went from 67% of the state experiencing some form of drought in February to 0.6% in the latest assessment from the U.S. Drought Monitor.
The dramatic reversal of fortunes was brought along by waves of moisture hitting Colorado from the West Coast in March and April, coming down in the form of some truly memorable powder. This year’s State of the River featured speakers who explained what that snow will mean for Summit County going into the summer.
Among the speakers featured was Blue River Basin water commissioner Troy Wineland. Wineland spoke to the current state of the basin and what we should expect to see in the upcoming spring runoff, which has been greatly anticipated since a historically low snowpack last year. 
Wineland noted that current snowpack was 150% of the median. While that’s good news, the volume of the runoff and efficacy of the snowpack is dependent on how long it lasts.
On that front, there’s promising news. Wineland said that the National Weather Service’s eight-to-14-day temperature and precipitation forecast, the best current measure of when snowpack will start sloughing off the mountains and melting into rivers, shows that the next couple of weeks will be both colder and wetter than normal.
That is a good sign that the runoff will be stalled until the end of the month or early June.
Wineland said that the monthlong forecast shows a similar trend with precipitation, but a more even chance of above or below-average temperatures.
A late winter storm Wednesday through Thursday is expected to add more to the snowpack while delaying meltoff further.
Wineland also said forecasts were predicting peak flows of the Dillon Reservoir’s three tributaries to be well below bankfull, or when rivers reach the top of their banks before flooding. But that does not mean residents can let their guard down when it comes to flooding risk.
“Regardless of how much snow is up on those hills, you always have risk for flooding, even in below-average years,” Wineland said. “One of the biggest factors is how fast that snowpack falls off, which is when sustained temperatures are above freezing. It’s probably a good thing we have below-average temperatures in the near and long term.”
Wineland also noted that the basin has a soil moisture deficit 10 to 12 inches deep, and would absorb a portion of the runoff, “like a dry sponge.” But even if those factors don’t prevent flooding, Wineland was confident Summit County authorities are prepared for it.
“Everyone is on high alert,” Wineland said. “The county’s road and bridge workers are very proactive. The town of Frisco and Copper Mountain Resort have staged excavators just in case they find there is debris building up in the creek that needs to be cleared. What happens is completely dependent on when the snow starts melting.”
Courtesy Summit Daily