Roaring Fork River: Above average runoff forecast but low flood threat seen for Aspen, other towns
June 2, 2014
The Roaring Fork River's peak runoff is expected to be higher than average by about 580 cubic feet per second, or 10 percent, this year at Glenwood Springs, according to the Colorado Basin River Forecast Center.
But when peak runoff will hit for the Roaring Fork and Aspen-area rivers and streams remains the big question that Mother Nature will ultimately answer.
The river forecast center's latest report, issued May 19, said the greatest likelihood was for a peak flow of 6,500 cfs for the Roaring Fork near its confluence with the Colorado River. The average peak is 5,920 cfs.
The "normal" peak comes between May 29 and June 23, the center's website shows. Last year the Roaring Fork peaked on June 12.
So far, runoff season has been nearly perfect for river runners. Low temperatures have prevented a rapid melt-off.
"Right now it's coming up to be great," said Jim Ingram, owner of Aspen Whitewater Rafting.
His company has been running the Slaughter House Falls outside Aspen for about two weeks. The flow there exceeded 1,600 cfs on Thursday.
"It's awesome — getting to be close to peak water," Ingram said.
The old-school way of predicting peak runoff is to look at Bell Mountain, according to Ingram. When the bell-shaped peak on Aspen Mountain loses its snow, peak has occurred, he said.
River runners hope that high daytime temperatures continue to be tempered by cool weather at night. That will prolong the high-water season.
Public agencies in the Roaring Fork Valley want the same weather pattern because it will ease the threat of flooding. Basalt and Snowmass Village Fire Chief Scott Thompson said his greatest concern is the possibility of microbursts combined with high temperatures. That adds rain to the water produced by the melting snow.
"I'm concerned about every runoff, especially with the snow (amounts) we have," Thompson said.
That said, no existing signs indicate that flooding will be an issue within the fire district's boundaries, according to Thompson. The Pan and Fork Mobile Home Park in Basalt has been dismantled, so what had been a particularly susceptible area in the past is no longer a concern, he said.
In addition, a contractor for the town of Basalt removed cobblestone and sand from the main channel of the river at the trailer park, so that will remove a pinch point and increase the capacity of the river to handle volume. Removing that pinch point, Thompson said, will likely ease the risk of water backing up into the mobile home park.
Thompson stressed that minimal concern can turn to a high level of concern if there are rainstorms and high temperatures causing rapid melting off of the existing snowpack.
Runoff occasionally produces minor flooding of low-lying areas in the Crystal River Valley between Carbondale and Redstone. The average peak runoff for the Crystal River is 1,930 cfs, according to the river forecast center. It is anticipated to be 2,000 cfs this year, the center said.
While much of the lower snowpack has melted out, totals are still high above 10,000 feet, according to the Natural Resources Conservation Service. Schofield Pass, for example, at the Crystal River headwaters was at 173 percent of average for May 29.
The U.S. Bureau of Reclamation dumped more water earlier than usual from Ruedi Reservoir this year to make room for runoff. The reservoir is currently 74 percent full. The agency anticipates it will fill in early July, slightly earlier than usual, which is good news for boaters.
"We're still seeing above-average snowpack in the Upper Fryingpan Basin," said Kara Lamb, spokeswoman for the agency. The Reclamation Bureau anticipates a runoff season similar to 2006 and 2009, when the snowpack was at about the same level as this year. That assumes no unusual weather strikes in June, such as a prolonged heat wave or an epic rainstorm, Lamb said.
Conditions should be more predictable than they were in 2010 and 2011, when wave action on the full reservoir caused water to splash over the spillway of the dam.
"There was uncertainty as to what was going to happen," Lamb said.
As it turned out, there was no major flooding.
The bureau estimated on May 1 that about 64,900 acre-feet of water will be diverted from the Upper Fryingpan River and Hunter Creek diversion systems this year. That's up from 54,000 acre-feet last year.
The water release from Ruedi into the Lower Fryingpan River is currently at 244 cfs after a bump of 30 cfs by the reclamation bureau Wednesday. That falls within the range of 100 to 350 cfs that anglers consider optimal on the Fryingpan River, said Kirk Webb, assistant manager of Taylor Creek Fly Shops.
The water release could change drastically sometime after Friday because of the Upper Colorado River Endangered Fish Recovery Program. Water releases among Western Slope reservoirs are coordinated in years with ample snowpack to mimic historically high spring runoff on the Colorado River. That creates conditions that benefit three native species of endangered fish on the Colorado River near Grand Junction.
Federal agencies are evaluating the water-release options at a meeting today. Water releases from Ruedi and other reservoirs will likely be boosted, but it is unknown when it will start and for how long it will continue, Lamb said.
Webb said it is still possible to catch fish in the Fryingpan even with flows as high as the 800-cfs range. The high water changes fish patterns and angler strategies, he said. For example, it pushes fish toward the banks and affects insect hatches.
On the Roaring Fork River, visibility during runoff affects fishing more than speed or depth of the water, according to Webb. The river is carrying a lot of sediment right now, but that gives the fish a chance to rest and recoup, he said.
"We're just excited that we have water, to tell you the truth," Webb said, referring to two previous dry seasons.
River runners echo that sentiment. Aspen Whitewater Rafting and other companies are offering preseason special prices to Roaring Fork Valley residents this spring. Those will continue until tourist numbers climb in mid-June.