Colorado headwaters break record flows
July 11, 2011
This year’s mountain runoff is expected to shatter all-time record inflows into the Colorado-Big Thompson Project.
With 334,000 acre-feet of water entering into the system from April 1 to the present, this year’s inflows are poised to surpass the record water levels of 1984, according to Northern Colorado Water Conservancy spokesperson Brian Werner.
“They’re quantities we haven’t seen before,” Werner said on Monday.
The Colorado River headwaters peaked for a third time over the weekend. The North Fork in Rocky Mountain National Park experienced flows up to 1,800 cubic feet per second, nearly doubling the all-time record of 995 cfs for this time of year on that part of the river.
Rainfalls at the western area of Rocky Mountain National Park during the weekend were minimal, with .16 inches of rain measured on Friday and .14 inches measured on Saturday, according to the National Weather Service. But that doesn’t rule out the possibility of isolated rainstorms that may have taken place at high elevations, meteorologists say, which may have added to the existing heavy runoff.
As of Monday, Granby reservoir was at 3 feet from being full, and the lake was rising 1 foot per day. Because of the volume of water entering the water-delivery system, reservoir operators planned to again ramp up releases from the Granby Dam. As much as 1,500 cfs will be released over the spillway and through the outlet works starting this week.
According to Werner, Northern estimates there still remains double to triple the volume of inflows than the system currently can hold.
High flows at the Colorado River headwaters caused damage to a bridge on County Road 491 – the sole access to several homes and the Winding River Resort located just outside of Rocky Mountain National Park.
Grand County Road and Bridge was alerted to a possible washout of the bridge at around 9 a.m. on Sunday, July 10. Spanning the North Fork of the Colorado River, County Road 491 accesses the subdivisions Aspen Pine Estates, Aspen Pine Acres, Sun Valley Ranch Estates and Sun Valley Ranch.
Although the steel frame of the bridge did not sustain damage from high flows, “the high levels of water eroded the earth behind the east abutment,” creating a washout, said Grand County Road and Bridge Supervisor Ken Haynes. In order to backfill the area behind the abutment, the bridge was closed off to motorists, elevating the situation to emergency status because of the blocked access to and from neighborhoods and the resort.
When one lane reopened temporarily around 2:45 p.m. to allow traffic to cross in both directions, as many as 100 vehicles crossed the bridge, Haynes said.
The bridge was temporarily reopened at 4 p.m. when just as many vehicles crossed; work was completed a short time later.
Workers “placed large rocks in the river to transfer the course of the turbulence from the sides to the middle of the river to lessen the impact on the supports,” Haynes said.
The Road and Bridge department and Rocky Mountain National Park personnel plan to monitor bridge stability in upcoming days.
With more rain in the forecast, the bridge “will have to be checked every 4 hours until the water level drops,” Haynes said.
Although the washout was unexpected, the bridge is on a list of “monitored structures” or bridges deemed suspect or dangerous.
The bridge on CR 83 in Fraser and the bridge over St. Louis Creek are also on the list.
– Tonya Bina can be reached at 970-887-3334 ext.19603.
Intern Ryndi Zastrow contributed to this story.