Summit County: Dillon Reservoir outflows boosted again

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The Blue River near flood stage near Silverthorne.

Blue River running high through Silverthorne

Staff Report

FRISCO — Flows in the Lower Blue River, below Dillon Dam, are going up again.

With snowmelt speeding up under warm and sunny skies, Denver is boosting the outflow to 1,800 cfs to avoid a scenario where Dillon Reservoir spills at a level that causes outflows to go over that level.

That’s exactly what could happen without upping controlled releases now, Denver Water spokesman Matt Wittern said via email.

“Our experts predict that, if we maintained 1,700 cfs outflow and inflows remain around 2,400, Dillon Reservoir would be full and spilling within a week,” Wittern said. That could bring excessive flows and the potential for flooding below Dillon Reservoir.

Wittern said Denver Water is estimating the remaining snowpack in the Blue River as equivalent to between five and seven inches of water near Hoosier and Fremont passes.

That snow is melting fast, with no letup in sight. Inflows from runoff into Dillon Reservoir averaged 2,467 cfs Tuesday, which was well above current and planned outflows. And those inflows aren’t expected to drop below 1,700 cfs in the next seven days, which means Dillon Reservoir will continue to fill quickly, at the rate of about six inches per day. As of Wednesday, the reservoir was 3.25 feet below capacity.

Wittern also explained that Denver Water can’t legally divert water through the Roberts Tunnel if it’s not needed.

“Right now water levels are very high on the South PIatte River, eliminating this action as an option,” he said.

Troy Wineland, state water commissioner for the Blue River, said property owners in the Lower Blue who face flooding risks can prepare by perusing Summit County’s High Water Preparedness” manual which includes instructions on sandbag preparation and placement, as well as free sand / bag supply locations.

Wineland also said water users in the Lower Blue should be aware that higher flows will push more water through diversions, possibly over-topping in irrigation ditches.

Morning photo: Sunday set

Summit spring


FRISCO —Sweet springtime in the Colorado Rockies. Snow on the high peaks, rivers swelling with runoff, fields and aspen groves greening up in the lengthening days and happy bluebirds! What could be better?

Climate: Early meltdown for Colorado snowpack

April 1 snowpack the 3d-lowest in 30 years; state preps for low runoff and summer streamflows

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Colorado snowpack started to decline in March, a month ahead of schedule.

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Colorado experienced widespread warmth in March.

By Bob Berwyn

FRISCO — Colorado water users need to prepare for below-average spring and summer runoff and streamflow based on the all-important April 1 snow survey, which showed a startling drop in the state’s snowpack since early March.

After tallying readings from automated SNOTEL sites and manual snow surveys, the federal Natural Resources Conservation Service said the water content of the snowpack is just 64 percent of average, down from 89 percent at the beginning of March.

“This is showtime when it comes to hydrological cycle in Colorado,” said state climatologist Nolan Doesken, referring to the fact that the state’s snowpack usually increases significantly in March and April. Continue reading

NASA tracks the Rocky Mountain global warming meltdown

Earlier snowmelt has been especially obvious in most of the mountain ranges of the western United States

Staff Report

FRISCO — A new NASA study focusing on northwestern Wyoming reinforces earlier research showing that global warming is already having a huge effect on the timing of snowmelt in the Rocky Mountains. Read the full NASA post, with more maps and graphs, here.

Taking a close look at the Wind River Range showed that the  snowmelt season in that area now ends about 16 days earlier than it did from the 1970s through the 1990s, using images and data from NASA’s Terra and Aqua satellites. They also studied ground-based stream discharge measurements and daily temperature and precipitation records. Continue reading

Global warming could reduce Sierra Nevada runoff by 25 percent

Increased plant growth projected to use more water

In the lengthening nights of October, the Snake River starts to freeze.

Global warming is likely to have a big impact on mountain runoff. bberwyn photo.

Staff Report

FRISCO — Forests and brush moving up mountainsides as the climate warms could take a big gulp from streams and rivers, potentially cutting runoff by as much as 25 percent by the end of the century. Warmer temperatures will accelerate plant growth, triggering more water absorption and evaporation, according to researchers with  UC Irvine and UC Merced.

“Scientists have recognized for a while that something like this was possible, but no one had been able to quantify whether it could be a big effect,” said UCI professor of Earth system science Michael L. Goulden. “It’s clear that this could be a big effect of climate warming and that water managers need to recognize and plan for the possibility of increased water losses from forest evaporation.”

According to the researchers, runoff from mountain ranges is vulnerable to temperature hikes that lengthen growing seasons and result in more vegetation growth at high elevations, according to the study, to be published this week in the Proceedings of the National Academy of Sciences. Continue reading

Climate: How hot will it get in Colorado?

State releases draft climate change report, comments wanted

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How warm will it get in Colorado?

By Summit Voice

FRISCO — Climate experts say it’s about to get warmer —probably much warmer — in Colorado. A draft state climate report released this week for public comment shows that Colorado has warmed by 2.5 degrees Fahrenheit in the past 50 years. By the middle of this century, summer temperatures will be higher than in all but the hottest years, with another 2.5 to 5.5 degrees of warming expected. Continue reading

Climate: Storms bolster Colorado snowpack

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Colorado’s snowpack is above average as of Feb. 1.

Feb. 1 snow survey results suggest decent spring runoff for most of the state

By Summit  Voice

FRISCO — Colorado’s snowpack surged to above average in late January thanks to a strong storm that brought snow statewide, federal water experts said last week. The Feb. 1 snow survey showed the average snowpack across the Colorado mountains at 107 percent of average, and 152 percent above last year’s Feb. 1 reading.

As of Feb. 1, only the Upper Rio Grande (82 percent) and San Juan (79 percent) basins in the southern part of the state were below average, according to the USDA’s Natural Resources Conservation Service. Continue reading

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