State of the Colorado River: An unusual year for snowpack, runoff
It’s been a fickle season for snowpack, and runoff could go either way in this unusual water year.
That was the message delivered by regional water managers at the Colorado River District’s State of the River meeting on Tuesday evening, May 26, in Granby.
During the meeting, officials from the Upper Colorado River Basin’s biggest water interests including Northern Water, Denver Water and the U.S. Bureau of Reclamation spoke about some of the basin’s biggest issues, including the state of runoff and snowpack in the region and the movement at Ritschard Dam on Wolford Mountain Reservoir.
Though snowpack seemed to falter during what proved to be a rather dry March, it’s been building steadily over the last three to four weeks, explained Don Meyer with the Colorado River District.
The variations in snowpack have pushed the basin into “uncharted territory,” he said.
“I think the message here is think 2010 in terms of snowpack,” Meyer said.
Though he added that snowpack is not analogous to runoff, Meyer said 2015 “will likely eclipse 2010 in terms of stream flow.”
Victor Lee with the U.S. Bureau of Reclamation echoed Meyer, adding that recent cold temperatures across the region have allowed snowpack to persist.
Though snowpack is currently below average, it could linger past the point at which the average snowpack tends to drop.
However, everything is still up in the air, Lee said.
“I just want to stress that there’s a lot of uncertainty with the snowpack,” he said.
If the current snowpack does translate into high runoff in Grand County, there may not be anywhere to put it, Lee said.
Front Range reservoirs are full, and storage in Lake Granby is the highest it’s ever been for this time of year, according to Lee’s presentation.
“We’re way above what we’ve ever seen in the past,” he said.
The result will likely be higher flows from Lake Granby.
Though it could be a good runoff year for Grand County, Meyer said that snow-water equivalent above Lake Powell is still well below average, making it a dry year for the Upper Colorado River Basin overall.
Officials aren’t sure when the settling and movement at Ritschard Dam will stop, but it poses no threat to safety, said John Currier with the Colorado River District.
“We really are absolutely confident that we don’t have an imminent safety problem with this dam,” Currier said.
The dam has settled around 2 feet, more than twice the anticipated depth, since 1995.
Inclinometer readings from parts of the dam’s core have shown one section moved around 7 inches downstream, Currier said.
Problems are focused on the rock-filled shells that line either side of the dam’s clay core, Currier said.
Moisture control was not used during the construction of the shells, leaving them less dense than they needed to be, he said.
The structural issues were discovered during routine maintenance work.
As of now, there are no definitive plans on how to repair the dam, though Currier said he anticipated “some type of structural remediation.”
What kind of remediation or an approximate cost is currently unknown, he said.
“I would like to say by this time next year we would have a very firm plan in hand of what we want to do with the remediation of this dam,” Currier said.
Some possibilities include removing the top of the dam and reprocessing the shell material before returning it in a more dense state, Currier said.
To relieve some pressure on the dam, the district will operate Wolford Mountain Reservoir at 10 feet below full pool this year to reduce deformation, though Currier said that’s not a sustainable resolution.
“Our goal is to keep everybody apprised of what’s going on and how it might affect you,” Currier said.
The Bureau of Reclamation will increase flows from the Granby Dam to 1,500 CFS around May 29 and maintain those flows until around June 8, Lee said.
The releases will be part of an endangered fish recovery program and will be coordinated with releases from other basin reservoirs to enhance peak flows in the Grand Valley where the plan is focused.
Wolford Mountain Reservoir will also participate in the coordinated releases, Meyer said.
The program hopes to re-establish bonytail chub, Colorado pikeminnow, razorback sucker and humpback chub populations to a 15-mile stretch of the Colorado River above Grand Junction.
Windy Gap Firming
After receiving its Record of Decision last year, the Windy Gap Firming Project’s next major hurdle is acquiring a Section 404 permit from the Army Corps of Engineers for the construction of Chimney Hollow Reservoir, said Don Carlson with Northern Water.
The permit regulates dredged or fill material into water as part of the Clean Water Act.
Northern Water hopes to acquire the permit this year, with construction possibly beginning in 2016 or 2017, Carlson said.
The project seeks to firm up the Windy Gap water right with a new Front Range reservoir. The project currently stores water in Lake Granby.
Because it’s a junior water right, yield for the project is little to nothing in dry years.
Northern Water also hopes to establish a free-flowing channel of the Colorado River beside the Windy Gap Reservoir as part of the Windy Gap Reservoir Bypass Project.
The new channel would allow for fish migration and improve aquatic habitat along the Colorado River.
That project still needs $6 million of its projected $10 million cost.
Moffat Tunnel Flows
Moffat Tunnel flows are hovering around 15 CFS as Denver Water is getting high yield from its Boulder Creek water right, said Bob Steger with Denver Water.
The increased yield from that junior water right means flows through Moffat Tunnel will remain low through early summer, Steger said.
“The point is we’ll be taking a lot less water than we normally do,” he said.
Denver Water expects its flows through the tunnel to increase in late summer as its yield from Boulder Creek drops, Steger said.
Williams Fork Reservoir, which is used to fulfill Denver Water’s obligations on the Western Slope, is expected to fill in three to four weeks, Steger said.
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