Snowpack/runoff news: McPhee spill looking iffy

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From the Cortez Journal (Shannon Livick):

“If there is going to be a spill, it is going to be small and short,” said Mike Preston, general manager of the Dolores Water Conservancy District. The Dolores River peaked at 2,530 cubic feet per second Monday and then dropped to about 1,810 cfs Tuesday along with the cold weather. McPhee Reservoir was at an elevation of 6,917 feet Wednesday. When full, the lake is 6,924 feet. In the 24 hours previous, the lake rose about 8 inches. So if there is a spill, so that rafters and kayakers can enjoy the Lower Dolores, it will be within a week or so, but only if the weather cooperates. “It really depends on the temperature,” Preston said. “And the wind, too.” Wind blows snow up in the air, and the snow evaporates, Preston said. Wind also creates a dust layer over the snow that can make it melt faster…

Preston said he hopes, if there is a spill this year, to be able to give community members 48 hours notice so they can plan any rafting trips accordingly. To keep tabs on this, go to http://www.doloreswater.com and click on “releases” to the left of the page. If the cool weather continues and irrigation use goes up, there likely won’t be a spill…

Last year, there was a 10-day spill with an average flow of 1,400 cfs. On Wednesday, the Lower Dolores was running at about 60 cfs.

From The Summit County Voice (Bob Berwyn):

[Blue River Basin water commissioner Scott Hummer] said the snowpack at lower elevations is going fast, with automated SNOTEL sites in the Blue River Basin reading 69.5 percent of average basin-wide. Above Dillon Reservoir, the snowpack is about 77 percent of average, but a station at Summit Ranch, in the Lower Blue, is only reading at 4 percent of the historic average. Streamflows in the basin are also below average because of the cool weather, Hummer said, adding that there is very little chance of runoff flooding this year. But as always, flash flooding can become a concern if there is a big rain event while streams are running high. Despite the low snowpack, reservoir storage in Summit County and across the state is higher than average, so Hummer is not expecting any severe shortages this summer. Right now, most of the water from the Blue River Basin is being captured for storage in Dillon Reservoir and Green Mountain Reservoir, which should help bring both the reservoirs up to optimum levels for recreation as the summer boating season approaches…

Ron Thommason, of the federal Bureau of Reclamation, explained how Green Mountain Reservoir fits into the overall water management scenario in Colorado. “When we divert water out of Granby and Willow Creek … we offset the amount with water from Green Mountain Reservoir,” Thommason said, adding that one-third of the water in Green Mountain is set aside for that purpose. Green Mountain was built specifically as a storage bucket to help water managers meet all the diverse needs at the right time, including irrigation and domestic use, and even upstream snowmaking at Summit County’s ski areas. Some of the reservoir’s water is also used to enhance habitat for the Colorado River’s endangered fish in what’s known as the 15-mile reach near Grand Junction, he said…

We’re getting close to where we need to be for me to feel comfortable releasing a little extra water from Green Mountain,” he said. “We’ve got another couple of weeks to see what happens … For the near term, we’re going to be releasing about 100 cubic feet per second from Green Mountain,” he said, adding that outflows will likely be ramped up as runoff increases. “We’re going to plan on filling the reservoir by the end of June. I usually aim for July 4,” he said. After that, a gradual draw-down begins. By the end of the fishing season in late October, the reservoir will have dropped by 45 feet, he concluded…

Denver Water’s Bob Steger said he’s confident that Dillon Reservoir will fill this spring. Six of Denver Water’s 10 major reservoirs are already full, Steger said. “They’re all going to fill, that’s the good news.” Water levels in Dillon Reservoir already are high enough to allow full marina operations as soon as the ice melts, Steger said, adding that it should be great year for flat-water recreation on the reservoir.

Conditions for rafting and kayaking below Dillon Reservoir are still weather-dependent, Steger said. “If things dry out, we’ll start spilling sooner,” he said. If the weather is dry the next few months, there will only be a window of a few weeks with raftable flows in the Lower Blue, he said. If the weather is wet from now on, the rafting season could be extended by several weeks, he said, explaining how Denver Water tries to balance various factors, including optimum flows for fishing, protecting Silverhorne from potential flooding and making sure storage in Dillon Reservoir stays at an optimum level.

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