What to expect from Summit County’s spring runoff season, according to the experts | SummitDaily.com

What to expect from Summit County’s spring runoff season, according to the experts

Dillon Reservoir is currently only 78% full, and Denver Water experts are unsure if it will fill this year. Spring runoff season is still experiencing drought conditions but is expected to be better than 2021.
Liz Copan/Summit Daily News archive

Temperatures are getting warmer and snow has begun to melt, signaling the beginning of spring runoff season.

Local water experts gathered together for a workshop about what to expect, and many said that drought conditions will continue. Troy Wineland, Summit County’s water commissioner for the Blue River Basin, said that all 64 counties in Colorado have been given drought-affected designations, per the United States Department of Agriculture.

“We’re truly in uncharted territory with respect to the Colorado River Basin,” he said, adding that across the West, reservoirs are failing to fill or reach capacity.

When it comes to spring runoff, Wineland said there are various factors to consider: what precipitation was like during the winter, conditions such as soil moisture and weather. For Summit County, precipitation since October has been feast or famine — with some months being well below average to others being on par or close to it in other months. Wineland said snowpack is sitting at about 85% of average, and soil moisture is slightly better than it was in 2021. He added that Summit County sometimes receives large amounts of snow in late April and early May, but current forecasts show that precipitation like that will be unlikely.

“When those soils are really dry, when that snow starts melting, we have to fill that deficit in the soil before that water can then run off into the streams and reservoirs,” Wineland said. “I’ve been stopping around a couple of ranches down-valley, and the snow is melting off on those ranches. Just walking around out in their meadows, (we see the) snow is melting, but the soil is not saturated.”

Kevin Houck, chief of watershed and flood protection for the Colorado Water Conservation Board, said that Summit County is doing better than other parts of the state — particularly the southwest, where run-off had already begun, and there’s not much snow left to melt.

“There’s always two factors in snowmelt flooding. One is, do you have the snow to begin with? And two, do you have a way to get it off the mountain quickly?” Houck said. “You have snow up there. It’s not that it’s not around. It’s less than average.”

Houck said when it comes to flooding, he recommends watching upcoming forecasts for several days of warm weather in a row, but if there’s a cold day of snow in-between, it does not count.

“In terms of how fast (runoff) comes off, that can be a little hard to predict more than a few days out,” he said.

As for Dillon Reservoir, it is still at 78% full and has been that way for the past few weeks. Ashley Denault, senior community specialist for Denver Water, said that 2022 will be better than 2021, but not by much. Inflow projections are still lower than average — about 81% of the average — but last year, it was only about 58% of the average.

“Our current outflow is about 95 cubic feet per second, and we are right now looking at projected outflow between 54 and 100 (cubic feet per second),” Denault said. “A lot of that really depends on the weather conditions in the area. …But we are not sure at this point in time if Dillon will fill. We are looking at it being close but probably not filling. Therefore, we are expecting a lighter than average runoff season.”

Green Mountain, however, is filling the resevoir, according to Victor Lee, a civil engineer with the Bureau of Reclamation in Loveland, but it is at its third lowest since 1985. Lee said that his forecast and operation plan has Green Mountain hitting a maximum fill somewhere between 7,940 and 7,945 feet, which is still short of a physical fill this year.

“This will mean that Green Mountain would end up in another year where we would be leaning on other reservoirs (like) Wolford to make sure that Green Mountain continues to meet its authorized purpose, which includes making water available for Summit County,” Lee said. “This year, I do not expect Green Mountain, during the fill period between now and in June, for the release ever to exceed 100 cubic feet per second.”

Currently, the National Weather Service in Boulder is predicting snow showers this week. On Monday, showers are likely to start before 4 p.m., then a chance of rain and snow showers. Chances for precipitation begin again late in the day Tuesday and continue through Thursday afternoon and should clear up by the weekend.

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