The breaking of an ice dam in the Roaring Fork River on Thursday killed several fish, knocked an angler off his feet and forced the downvalley migration of a beaver, witnesses reported.
Ice on the river broke up in the Lazy Glen Mobile Home Park vicinity two miles east of Basalt and sent a surge of ice and water downvalley, observers said.
"It was pretty impressive," said Tim O'Keefe, education director for Roaring Fork Conservancy, a nonprofit organization focused on water-quality and -quantity issues.
The floes occur when ice on the river breaks up and smashes into other ice. Water and ice pile up until the pressure is great enough to bust through.
A fisherman was on the stretch of the Roaring Fork River between the confluence with the Fryingpan River and Old Pond Park when the surge of water and ice rushed through, said Basalt Sgt. Penny Paxton. The angler reported he was roughly 10 feet into the water, off the bank, she said.
"He said, 'I looked up and saw a wall of water coming at me,'" Paxton said.
The fisherman was knocked off his feet but was able to make his way to the bank. Fortunately he had a wader belt, designed to keep water out. He was bruised, cut and very cold after getting wet but otherwise unharmed, according to Paxton.
He was walking on Emma Road in the vicinity of the Basalt Post Office when a motorist stopped, got him in the car and called authorities around 1:45 p.m. An ambulance crew from the Basalt Fire Department checked him out, but no transport to a hospital was necessary.
"He was extremely lucky," Basalt Fire Chief Scott Thompson said.
Paxton said the angler appeared to be in his mid-50s and was visiting from the Boulder area. His name wasn't available.
Prior to that call, Paxton said she was watching the ice and water surge at Hooks Bridge in the Emma area. She said ice chunks "the size of Volkswagens" and two feet thick were rushing downstream. The ice chunks got caught just upstream from the bridge, and water piled up until it suddenly released. Logs caught in the jumble were cracking as they were crushed by the ice. The mix of water, ice and debris crashed along under the bridge. Curious observers watched from the bridge.
"It took awhile. A lot of water got pushed through," Paxton said.
O'Keefe missed most of the floe but saw the aftermath from the 7-Eleven bridge in Basalt. He estimated there were some dead sculpin, a bottom-feeding fish, as well as a few dead trout visible from the bridge. Water rises incredibly quickly when the ice jams go through, O'Keefe said, and then drops just as quickly. Some of the fish get caught high and dry.
Observers reported to O'Keefe that a beaver was riding ice chunks down the river. The animal was able to make its way onto shelf ice connected to the riverbank within sight of the bridge. The beaver was alive, just not moving very quickly.
"My guess is he went for a wild ride and was warming up," O'Keefe said.
The breakup of an ice dam is a natural event that produces environmental benefits and degradation, according to O'Keefe. The ice scours the bottom of the river bed and kills the bugs trout depend on and results in the deaths of fish. However, the huge ice floes break up bank ice, which narrows the river channel and makes the river run quickly. Negotiating that water saps the energy of trout trying to survive the winter, he said.
"Like everything, there's some good and bad out of this," O'Keefe said.
More ice dams are likely to break up in coming days with higher temperatures. The Roaring Fork River through Snowmass Canyon is still frozen over, as is the Fryingpan River.