The Big Thompson River roars past a home and over a waterfall at the city of Loveland's Chasteens Grove Water Treatment Plant west of Loveland on Tuesday. / Rich Abrahamson/The Coloradoan
The water-diversion system above now-obliterated homes and roads through Big Thompson Canyon was never meant for flood control, according to the U.S. Bureau of Reclamation.
That’s why 24 hours of water releases from Olympus Dam in Estes Park on Sept. 12 prevented abrupt surges but did little to stop deadly floodwaters from ripping through down-canyon roads and homes, officials say.
“We did the best with what we had,” bureau spokeswoman Kara Lamb said. “The (storm) cells were right over all of this part of the state, and they weren’t moving.”
Releases from Lake Estes on Sept. 12 got bigger “at least every hour, if not more” to balance them with in-flows above Estes Park, Lamb said. Releases peaked at 5,280 cubic feet per second at 11:30 p.m., more than 50 times the September average. And the river added volume as tributaries gushed into the canyon down river toward Loveland.
“I have no idea what nature was contributing to the canyon on its own,” Lamb said.
When possible, 550 cubic feet per second of water was diverted to Horsetooth Reservoir and Carter Lake. Even that option was limited as runoff filled the canals, she said.
The federal government in 1937 approved the Colorado-Big Thompson project to move extra water across the Continental Divide, irrigating about 720,000 acres of farmland, according to the Bureau of Reclamation website.
“Their foresight was pretty great, what they foresaw for demand of water in eastern Colorado,” Lamb said, adding that flood control “probably” would have been added if they could’ve foreseen two catastrophic floods in the next 76 years.
But it’s a water-supply system, not a flood-control system. Changes would take heavy lifting, likely an act of U.S. Congress, she said.
Lake Estes can store only 3,000 acre-feet of water, a far cry from Horsetooth Reservoir’s 152,000 acre-foot capacity. Most Septembers, flows into Big Thompson River average about 100 cubic feet per second. Notice is sent to residents and officials on an email list whenever the river changes more than 50 cfs.
“We stepped up releases all day long,” Lamb said. “We were working in very close coordination with (Larimer County Sheriff’s Office) and emergency management to let them know what we were sending down the canyon.”
An emergency Loveland City Council meeting was called that night, with Loveland Fire Chief Randy Mirowski telling the public they were preparing for the already dangerous situation to “escalate.”
By 1:30 a.m., people living along the canyon reported hearing homes ripped from their foundations as they scrambled for higher ground. By Sunday, the sheriff’s office had reported two presumed deaths in the flooding, both in Cedar Cove just inside the mouth of the canyon and a few miles west of Loveland.
One of the apparent victims, a 60-year-old woman, was last seen in the surging river waters at about 2:30 a.m. Friday, according to the sheriff’s office.
Lamb said historical records show people begin noticing increasing floodwaters when they hit about 1,500 cfs, a number surpassed early the morning of Sept. 12.
Emergency notices were sent out Thursday after sustained rains for multiple days led to rock slides that pulverized U.S. Highway 34, amid other flood-related damage. Thousands of evacuation notices were sent that day, with some advising residents that parts of the highway were already impassible.
By Thursday night, when waters peaked, many along the canyon had already lost power. Cellphones don’t work in the canyon.
Sheriff’s office spokesman John Schulz said Thursday that it’s standard practice for deputies to go door-to-door when evacuation notices are issued. Details on the evacuation efforts won’t be available until perhaps next week, as the agency remains focused, a week later, on airlifting survivors to safety.
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