With Boulder Creek flowing at as much as eight times its normal rate, Sheriff Joe Pelle announced Thursday that tubing has been indefinitely banned there.

"At this point, it is just too dangerous," Pelle said. "The water is up into snags and trees, and you have people who are tubing that are generally inexperienced and not wearing safety gear."

Pelle, who consulted interim Boulder police Chief Greg Testa, said the decision was informed by a purely objective measure: Flotation device bans are usually initiated at 700 cubic feet per second, and Boulder Creek was flowing Thursday above 800, up from its normal rate of 100 to 300.

"The waters right now could very easily be deadly," said Pelle, who added that several people have drowned in the creek since he became sheriff in 2003.

There is no set end date to the ban, as it's dependent on how fast the water is flowing.

The closure, which includes the entire stretch of the creek that runs through the city of Boulder, begins at Barker Dam near Nederland and runs to the Weld County line north of Erie.

Under the ban, single-chamber rafts, single-chamber belly boats and inner tubes are prohibited. Violation will result in a $50 fine.

Kayaks and whitewater canoes are permitted, however.

"With those activities, it's different," Pelle said. "People wear safety equipment and are generally equipped to handle it, and they're more experienced."

The tubing ban can be traced back to recent warm temperatures leading to snowmelt, thereby increasing Boulder Creek's flow.

It's affecting other local bodies, too, including the St. Vrain River, which is expected to be closed this weekend, according to officials. It's now running at 1,043 cfs. The threshold to close that river is 1,200 cfs.

The rising levels aren't just a threat to tubers, said Lyons meteorologist Greg Berman, who warned in a "flood watch" update that Boulder Creek could be near its tipping point.

As of 6:30 a.m. Thursday, the creek was running at 835 cfs at North 75th Street.

Due to high water, the city had also closed Boulder Creek Path underpasses at Sixth Street, 13th Street and Arapahoe Avenue, Boulder High School, Folsom Street, 30th Street, 38th Street and Arapahoe, 55th Street and Valmont Road.

Mike Banuelos, Boulder public works spokesman, said this is common during the spring.

"Every year when Barker Reservoir fills and spills, there's localized flooding in underpasses, so that's something that we expect," he said. "Obviously, with the rainstorms like we got last weekend, that just adds some volume to (Boulder) Creek."

In addition to Barker's spill and recent storms, Berman said a new low-pressure trough from the west, as well as some moisture from Tropical Storm Amanda coming from the south, could bring the Front Range another three-quarters of an inch of rain through Saturday morning.

"Although this will not be the rule in the upcoming forecast, if these rains target any of the swollen river/creek areas, then there could be some flooding or added flooding to those areas already experiencing water overflow," he said.

Despite the region-wide water level concern, not all bodies are necessarily in danger; South Boulder Creek, for example, is flowing at roughly 315 cfs and is not expected to be closed at any point this season.

Longmont Times-Call Staff Writer Scott Rochat contributed to this report.

Contact Camera Staff Writer Sarah Kuta at 303-473-1106 or kutas@dailycamera.com. Contact Camera Staff Writer Alex Burness at 303-473-1389 or burnessa@dailycamera.com.