Grand County rivers expected to peak this week
June 21, 2011
GRAND COUNTY – The National Weather Service is continuing its flood advisory on the Colorado River, with a secondary peak expected to occur around June 24.
Adding to flows will be increases from Lake Granby, which should top out at 2,400 to 2,500 cubic feet per second (cfs) by Monday to keep pace with runoff.
“We’re on our way up to 2,500 cfs,” said Kara Lamb, spokesperson for the Bureau of Reclamation, which owns the Colorado-Big Thompson water delivery system. About 430 cfs will be released through the dam gates, the rest by way of the spillway, she said.
As of Thursday, Lake Granby releases were up to 1,400 cfs, a large increase over the day before.
Meanwhile Willow Creek flows, which peaked last week, should see 960 cfs out of Willow Creek Dam. Especially at the confluence of the Colorado River and Willow Creek, flooding is expected for low-lying areas next week.
“We’re not willing to say we’re past all ideas of flooding,” said Northern Colorado Water Conservancy District spokesperson Brian Werner, although due to mild June temperatures, 2011 has been an “ideal water runoff year,” he said.
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Northern’s forecast was that 400,000 acre feet (an acre foot is enough to cover one acre with one foot of water) would run into Lake Granby this year – considered an all time record.
So far, about 150,000 acre feet of that has made it to the lake. And at Lake Irene near the Continental Divide in Rocky Mountain National Park, measurements this week showed an equivalent of 21 inches of water in the snowpack, whereas about 5 inches would be considered normal.
This means there is still a great deal more water to come, yet an overall composite for the Upper Colorado watershed shows that 83 percent of the snowpack has melted.
Lamb said it’s likely Lake Granby will fill by early July.
Downstream on the Colorado
Where it had been receding this week, flows in Muddy Creek on the Upper Colorado River just above Kremmling are expected to increase by next weekend then taper off.
On the main stem of the Colorado River, water forecasters are predicting the Kremmling gauge to show a secondary peak of about 9,000 cfs during the June 24-25 weekend.
“Whether it’s a seasonal peak is yet to be seen,” said Don Meyer, water research engineer for the Colorado River District.
Because of high flows, irrigators have pulled out about 8 to 10 large pumps on the Colorado River, he said, and are eager to put them back in to irrigate high ground.
“The prolific extended high level of flows, it’s just amazing,” Meyer said.
The saving grace to prevent flooding has been temperatures “flirting around normal,” rather than the sustained high temperatures of last year.
“We couldn’t have asked for a better way for the snow to come off,” he said.
Meanwhile, Denver Water has decreased its diversions through the Moffat Tunnel, meaning more water is flowing in the Fraser River.
“But we’re not planning on turning (Moffat diversions) off,” said Denver Water’s Manager of Raw Water Supply Bob Steger, on Thursday.
On Monday, June 13, water being diverted to Gross Reservoir through the tunnel was at a rate of 800 cfs, but by Thursday, that rate had dropped to a goal of about 400 cfs.
Because Gross was getting close to full, Denver Water was slowing down the fill rate “to make sure the tunnel is diverting during the peak,” Steger said.
According to water forecasters, the Fraser River will remain at about 1,100 cfs, then peak next week at about 1,700 cfs.
Tonya Bina can be reached at 970-887-3334 ext.19603.