Incoming tide – Part 2: Flash floods might make region forget 1999

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Last week, CSBJ writer John Hazlehurst began a three-part series on the history of flooding in the region and the ominous outlook after the Waldo Canyon fire. Part 1 focused on the historic 1935 flood, which killed 18, and Part 2 this week looks at the rising danger of flash floods even worse than in 1999, when Williams Canyon (photo, with sandbags still around) created a massive funnel of water that tore into Manitou Springs.

Last week, CSBJ writer John Hazlehurst began a three-part series on the history of flooding in the region and the ominous outlook after the Waldo Canyon fire. Part 1 focused on the historic 1935 flood, which killed 18, and Part 2 this week looks at the rising danger of flash floods even worse than in 1999, when Williams Canyon (photo, with sandbags still around) created a massive funnel of water that tore into Manitou Springs.

Editor’s note: Last week, CSBJ writer John Hazlehurst began a three-part series on the history of flooding in the region and the ominous outlook after the Waldo Canyon fire. Part 1 focused on the historic 1935 flood, which killed 18, and Part 2 this week looks at the rising danger of flash floods even worse than in 1999, when Williams Canyon (photo, with sandbags still around) created a massive funnel of water that tore into Manitou Springs

 

Downtown Manitou Springs looks much as it did 50, 75 or even 100 years ago. Monuments of the past still stand, proudly renovated. Barker House, the Spa, Cliff House, Wheeler Bank building, the Wheeler clock and the statue of Hygeia — all preserved, as are the 19th and early 20th century commercial buildings that line Manitou, Ruxton and Canon avenues.

This long-enduring framework gives the city a sense of permanence and safety. Look at the buildings along Fountain and Ruxton creeks, some precariously balanced over the water. You’d think any substantial flood would wash them away, and yet here they are.

Is Manitou safe from a massive flood event? Could a 100-year flood sweep down the two mountain streams, or burst out of Williams Canyon, and destroy much of the city?

Flash floods, so called because they occur after relatively short, intense rainfall events that send sudden flood crests down streambeds, are “the most common natural hazard” in Colorado Springs and the Pikes Peak region.

“Flash floods tend to occur from May through September,” according the city’s office of emergency management, “and are usually caused by thunderstorms that are out of sight and hearing range of people downstream. Runoff from the mountains can quickly cause the water levels of small creeks and dry streambeds to rise to unsafe levels. These walls of water are fast moving and can easily reach heights of 10-20 feet.”

Because afternoon thunderstorms tend to intensify and gain energy as they migrate from the mountains to lower altitudes, flash flooding in waterways such as Jimmy Camp Creek and Sand Creek has been more common than in Manitou or western Colorado Springs.

That may no longer be the case, thanks to the Waldo Canyon fire, which charred more than 18,000 acres of heavily forested mountain terrain above the city. Restoration work has been underway for months, but wildfires create hydrophobic soils, almost impervious to water. Imagine the effects of paving 30 square miles of mountain backdrop, and it’s easy to understand how flood events can threaten lives and property.

Flash floods have occurred with some frequency in Manitou and Old Colorado City during the past 150 years. While records from the 19th century are scanty and anecdotal, severe flash floods apparently occurred in 1864, 1882 and 1885.

On June 10, 1864, Fountain Creek rose 20 to 30 feet, sweeping away “almost all” of Colorado City. Sounds impressive, but it’s worth noting that the Colorado City of 1864 was a rag-tag assortment of cabins and flimsy frame structures huddled along the creek. In 1882, a flash flood burst through Williams Canyon, killing a 14-year-old boy, followed three years later by a storm that dropped “16 inches of rain and hail” near Manitou, reportedly destroying a railroad bridge.

In the 20th century, significant regional floods

occurred in 1921, 1935, 1965 and 1999. All of them affected Manitou, especially the 1999 event. In a 2003 study done in conjunction with proposed revisions of Colorado Springs drainage criteria, Matthew Garcia wrote: “The heaviest recorded rainfall exceeded 9.3 inches over 80 hours and was concentrated within the area of the City of Colorado Springs … meteorological patterns surrounding this storm event conformed with those [of the Big Thompson flood of 1976].”

In other words, Manitou dodged a bullet.

The 1999 flood was later analyzed by the Boulder-based National Center for Atmospheric Research (NCAR). From the report: “Manitou Springs was flooded by nightfall on April 29 when flood waters came rushing out of Williams Canyon. Williams Creek usually runs quietly beneath the sidewalk at Canon Avenue, but it quickly became jammed with debris and broke through the pavement. A 20-ton boulder crashed into a Manitou Springs home on May 1 after being loosened by four days of torrential rains.

“On the same day, officials closed Washington Avenue for fear that the road would begin sliding down the hillside which had been badly eroded by the rains. Several roads in the town were damaged or covered with debris after the floodwaters receded. … The four day rain total for Manitou Springs was 12.16 inches. They are the four wettest days on record for April in the region.”

Looming on the horizon

U.S. Highway 24 was closed at 21st Street for three weeks while the bridge over Fountain Creek was repaired. Flood damage in Manitou alone exceeded $5 million, while total damage came to more than $25 million.

Despite such impacts, the 1999 flood is classified as a 10-year event. That’s small potatoes compared to the 1935 flood, considered a 500-year event.

After the Waldo Canyon fire, the probability of catastrophic flash flooding has increased dramatically. The Manitou Springs emergency preparedness guide doesn’t mince words: “Flooding is not a matter of if, but of when.”

In the fire’s immediate aftermath, it was clear that the Douglas Creek, Camp Creek and Fountain Creek drainages could be major flood conduits, and that a 10-year flood could very quickly become a 100-year event. That’s what happened in the 10 years after the 2002 Hayman fire, when there were 10 hundred-year floods on the area’s major drainage way.

Upgrading regional stormwater drainage structures to meet such challenges has barely begun. But that’s just a small part of the problem. A study has estimated Colorado Springs’ unfunded maintenance, repair and improvement backlog at $680 million, with regional needs bringing the total to more than $1 billion. Even if a dedicated funding source can be created, it will take decades to catch up.

The Stormwater Enterprise, created in 2004 by City Council, imposed a stormwater drainage fee on every improved parcel of city land. Urged on by activist Douglas Bruce, city voters abolished the enterprise in 2009.

Dr. Eve Gruntfest, professor emeritus at UCCS, is a renowned geographer who has been working in natural hazard mitigation for 35 years.

“The end of the stormwater program is a big issue,” she said, “and very unfortunate. But I think that it’s important to stress that it’s very, very difficult to accurately predict flash floods, even without trying to take into account the impacts of the fire.”

Mountain wildfires may seem threatening and dangerous, but Colorado Springs residents have traditionally welcomed afternoon thunderstorms with these words: “We need the moisture.” Wildfires may burn for days before threatening lives and structures, but flash floods can occur with little or no warning.

Nearly 30 years ago, Gruntfest authored the Manitou Springs Flood Hazard Mitigation Plan. In a 1999 simulation (see accompanying story) based on her earlier work, a flash flood resulted in 47 deaths and the utter destruction of Manitou’s business district.

“There’s nothing magic about the geography of the Big Thompson Canyon that is different than the vulnerability of the Manitou Springs-Colorado Springs area,” Gruntfest said. “We have just been lucky — but luck is not enough to count on for the long term.”

Flood warning systems

Manitou’s flash-flood warning system is urgent and intrusive. An earsplitting siren will sound when the National Weather Service issues a flash-flood warning, combined with reverse 911 calls and messages on broadcast media, Twitter and Facebook.

Such urgency is important, says UCCS professor Jeannette Sutton, a disaster sociologist specializing in research on uses of social media in crises and disasters. She says that Twitter, Facebook and other social media help in disasters, but not as rapid warning systems.

“We are programmed to believe we’re not at risk,” she said. “That’s how we can drive our cars and go about our lives. Warning systems need to cause people to pay attention. Slowness in getting the word out puts people at risk.”

Colorado Springs abandoned its emergency sirens many years ago. Now the city actively reaches out to residents and businesses likely to be affected.

“We’ve had community meetings and even gone door to door in Pleasant Valley to inform people,” said Bret Waters, the director of the city’s emergency operations center. “We want people to realize that you don’t evacuate in a flood — you relocate to higher ground. Getting in your car can be dangerous — people will perish in vehicles.”

Using urgent media, such as reverse 911 calls, can be tricky.

“We don’t want to (have so many false alarms) that people just ignore them,” he continued, “but if there’s a question, we’ll notify everybody, even go door to door — if we have time.”

It could happen: The next flash flood, a chilling timeline for sudden disaster

(Editor’s note: In 1999, Eve Gruntfest, a geography professor at UCCS, created this timeline of what could be expected in the case of a massive flood in Manitou Springs. Thanks to the Waldo Canyon fire’s burn scar, a similar sequence of events is far more likely in Manitou now than 14 years ago.)

The day of the scenario is typical for the Colorado Front Range. The weather forecast calls for a chance of afternoon thunderstorms. An accumulation of cumulonimbus clouds over Manitou Springs and the entire Pikes Peak Region is not sufficient cause for alarm to the residents and tourists of Manitou Springs on this warm, summer afternoon.

3:30 p.m., the sky has blackened and rain is beginning to fall in the mountains.

4:20 p.m., the satellite detection system has alerted the National Weather Service Office in Pueblo of the situation. They issue a flash flood watch for all of El Paso County. They contact the El Paso Office of Emergency Management, which in turn contacts the area’s police and fire departments including Manitou Springs.

4:25 p.m., local stations relay the flash flood watch to the broadcast region.

4:30 p.m., the storm has unleashed its full fury over the Fountain and Ruxton Creek drainage basins. The heavy rain causes many picnickers and campers in higher elevations to seek shelter or head for home.

4:50 p.m., the Alert System — an integrated network of stream gages and rain gauges in the drainage basin — is reporting heavy rainfall to the El Paso County Office of Emergency Management. Unfortunately, some of the gauges are not reporting because of loss of communications.

5 p.m., the thunderstorm has intensified and shows no sign of moving out of the area. The town of Cascade reports three inches of rain in the last half-hour. Flooding is beginning to occur on the east side of Manitou Springs.

5:10 p.m., the Office of Emergency Management advises the Manitou Springs Police Department to evacuate people in the Fountain Creek floodplain.

5:25 p.m., the National Weather Service in Pueblo issues a flash-flood warning. Sirens sound across Manitou warning residents to get to higher ground. The police department sends out two police cars to warn people of the impending flood of Fountain Creek.

The sky over Manitou Springs has become coal black, interrupted only by sudden flashes of lighting. The intense rainfall is causing numerous rock and mud slides along the canyon walls and highway, trapping those people trying to escape by car. Flooding has already cut off the upper junction of Highway 24 and Manitou Avenue.

5:35 p.m., many residents are fleeing downtown for higher ground. Others are debating whether to join their fellow citizens or wait out the storm. Some of the more recent residents think that the situation is not as bad as last year’s flood, and decide to wait it out.

5:45 p.m., all residents of the El Paso Apartments are evacuated to Manitou Springs High School.

The first crashing wave of the flood waters hits Manitou Springs at the upper reach of Ruxton Creek. Because the channel is lined with concrete in its upper stretch, its flow is restricted and its velocity is increased.

The portion of the channel that flows beneath the Iron Springs Chateau Hotel is unable to retain the flow, sending a six-foot surge of water through the main dining room. Diners are caught completely off-guard by the flood.

Seventeen lives are lost.

A crashing wall of water hits the western part of downtown Manitou. Tourists and residents who remained behind are swept away with the wall of water. Nineteen more people are killed.

6 p.m., Colorado Springs officials are having difficulty entering Manitou Springs due to the severe flooding. Flood water in the overbanks is exceeding ten feet in depth and flow velocities are now exceeding fifteen feet per second.

The Manitou Springs fire and police departments face further difficulties as a crushing force of water knocks down the support beams for City Hall, causing the back half of the building to collapse into Fountain Creek.

Older structures located along Fountain Creek suffer the most damage as the flood reaches its peak. The numerous businesses that lie parallel to the creek and to Manitou Avenue are demolished as the creek roars past. Video and pinball machines from the Arcade are left in a mass of debris, leaving the Manitou Mall area devastated. The Spa suffers major damage

6:30 p.m., the rain has ended, and the floodwaters begin to subside. People who had climbed to safety are now finding a warm cup of coffee and a blanket from the Red Cross. Helicopters and flashing lights surround the surreal landscape. Survivors are crying over the loss of their loved ones and homes.

Forty-seven people died in the flood, with scores more still missing.

One Response to Incoming tide – Part 2: Flash floods might make region forget 1999

  1. The management of storm – flood water presents an excellent opportunity for a true spirit of ‘regionalism’ to blossom with the chance for the city, count and civic/business sectors to reach new levels of cooperation to resolve a community wide need. We will be running our on-line poll to determine how the public feels about this issue as well as our annual Trust and Confidence in Local Government Survey. If you would like to participate and sign up as a survey member, your responses, comments and suggestions would be greatly appreciated.

    Staci Lynne Holdt
    May 3, 2013 at 10:01 am