Angus Reichert gets through a little rough water during his kayak run on Boulder Creek as part of an Avid4Adventure camp Friday. While water levels are
Angus Reichert gets through a little rough water during his kayak run on Boulder Creek as part of an Avid4Adventure camp Friday. While water levels are down in area creeks and the spring runoff is past its peak, officials urge residents to remain vigilant and keep an eye on area waterways. For more photos and a video, visit www.dailycamera.com. (Cliff Grassmick / Daily Camera)

The calendar flipped Saturday from one season to the next, and the temptation might be to let go a sigh of relief and say that Boulder County has dodged a bullet.

Not so fast.

After weeks and weeks of community meetings and emergency preparedness bulletins about the dangers posed by a high water table, accumulated storm debris in the county's tributaries, and perennial "spring runoff," the last day of spring has passed with no serious flood events in the county.

That doesn't mean risks evaporate with the arrival of summer's heat, however.

"'Spring runoff' is the term we use, because that's when it starts happening," said city of Boulder Public Works spokesman Mike Banuelos. "But it doesn't just stop happening when spring ends."

Spring runoff did cause Barker Reservoir to fill and flow over its spillways — as it was designed to do — the fourth weekend of May and had been predicted to occur just days earlier. But, Banuelos said "As snow continues to melt, we will continue to see those flows into Boulder Creek.

"We still are encouraging people to really be vigilant and watch the waterways through town," Banuelos said. "We're beginning what's typically thunderstorm and monsoon season, and those types of events are really when we see more flash flooding events, and that's something that has always been true for Colorado and Boulder, in general."

Area has 'moved beyond' seasonal peak streamflows


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The city of Boulder, the Boulder Office of Emergency Management and the Long-Term Flood Recovery Group held open houses at the start of spring to promote flood preparedness measures in advance of the seasonal snowmelt in the high country, coming off one of the worst floods in Boulder County of the past century in September.

That event created added concerns beyond the normal worries. With added debris in the high country tributaries and somewhat changed characteristics of the very streams themselves, it was difficult to predict how the topography would respond to even the standard level of runoff.

With snowpack running at 169 to 258 percent of normal in late March, despite heavy mitigation work from Allenspark to Eldorado Springs, Emergency Management Director Mike Chard was urging county residents to "Be aware, and be prepared."

On Friday, Chard said just 10 days to two weeks ago, Lefthand Creek, the St. Vrain River and Boulder Creek all were at their peak flows, at 430 cubic feet per second, 1,200 cfs and 900 to 1,000 cfs, respectively. All of those, Chard said, were within seasonal averages. In recent days, those numbers have dropped to roughly 125 cfs, 500 and 350.

Banuelos, however, on Friday said Boulder Creek's mean flow rate through the city is still at 450 cfs.

"We are pretty confident we have moved beyond the peak flows," said Chard. "It doesn't mean we are totally out of the woods."

Heavy mitigation activity leading into the runoff season, focused largely on removing accumulated debris from critical waterways and tributaries, is being credited for the mostly incident-free spring season.

"Had we not done all that work and had all the help from the state and FEMA, it would have made it more tenuous," Chard said.

State's most lethal flood hit at end of July

Chard and Banuelos both stressed that as runoff continues into early summer, the greatest concern is thunderstorms that can set up over one area in the foothills and dump a heavy amount of rain into one tributary in a concentrated period of time.

"That type of storm pattern is the more typical storm that we see in the Front Range and really makes Boulder the number-one flood-flash-risk community in Colorado," Banuelos said, noting the concentration of development in or near the Boulder Creek and South Boulder Creek flood plains.

"September was unprecedented, in that it was a long-term period of time. We just got a ton of rain," Banuelos said. "A flash-flood event is something that is more typical" for Boulder and the Front Range.

The best reason to heed officials' advice to maintain attention to weather alerts and the state of the county's waterways might be historical; the most lethal flood in Colorado history, the Big Thompson Flood of 1976 which killed 143, struck on the last day of July.

To obtain the most current flood information available through in Boulder and to sign up for online alerts, Banuelos advised people to go to bouldercolorado.gov/flood.

And Chard pointed out that as runoff runs out, and the year proceeds, wildfire dangers will rise.

"We transition from one threat to the next," he said.

Contact Camera Staff Writer Charlie Brennan at 303-473-1327 or brennanc@dailycamera.com