Triathletes competing in the Ironman Boulder this weekend can breathe a sigh of relief.
The results from Monday's water test at Boulder Reservoir are in, and bacteria levels are well below the threshold that would require officials to shut down the swim beach.
Competitors in Sunday's inaugural Boulder Ironman triathlon worried amongst themselves and on social media about what would happen if the reservoir's bacteria levels were too high.
The triathlon begins with a 2.4-mile swim in the reservoir, which starts on the beach.
"All of our water test results came back well below threshold levels," reservoir manager Stacy Cole said Wednesday.
Reservoir staff must test the water in the swim area at least once every seven days, Cole said. If bacteria levels exceed the standard set by the state, the swim area is closed immediately, she said.
Water typically is sampled every Monday from the reservoir and then gets sent to a water treatment facility. Tests there measure the levels of a particular strain of the bacteria E. coli, Cole said.
Race organizer Dave Christen joked that if levels had come back too high, his staff would've started pumping water into the reservoir with garden hoses.
"There wasn't a doubt in my mind on this one," Christen said. "We're in good shape."
Though heavy rains are expected to fall in Boulder County all week, Cole said there's no indication that runoff causes elevated bacteria levels.
"We've done a bunch of different things to try and determine what it is, and we haven't been able to determine a direct link," she said. "It's a natural body of water. It could be geese, it could be runoff, it could be a number of different things."
In the past, city officials have blamed both runoff and goose droppings for bacteria spikes at the swim beach.
'Natural body of water'
The course for Sunday's triathlon will take competitors well beyond the reservoir's beach. Starting at 6:20 a.m., they'll travel to the reservoir's northeast corner before cutting across to the northwest corner and then heading back toward the swim beach.
The triangular-shaped swim course should take athletes between 48 minutes and two hours to complete, based on the results from other full-length Ironman races.
Roughly 100 reservoir staff will be on the water to help with any necessary rescues.
Once out of the water, athletes ride 112 miles on their bikes and then complete a 26.2-mile run. They'll cross the finish line at 13th and Pearl streets downtown, and must finish before a midnight cut-off time.
Typically city officials close the reservoir swim beach several times each summer due to elevated bacteria levels. The beach was closed on June 3 this year and reopened two days later once bacteria levels decreased.
Cole declined to say whether athletes should be concerned that bacteria levels could change throughout the week before the race on Sunday.
"It's a natural body of water," she said. "There's inherent risks to swimming in any body of water, whether it be a pool or a natural body of water."
The rains — and accompanying cooler temperatures — have affected the reservoir water temperature, which means the race could become "wetsuit legal."
If temperatures drop below 76.1 degrees Fahrenheit the morning of the triathlon, all athletes can wear wetsuits for the swim and remain eligible for awards and qualify for the Ironman World Championships in Kona, Christen said. At 76.2 degrees or above, anyone is welcome to wear a wetsuit, but they won't be eligible for awards or Kona, he said.
Race organizers test the water in three different places the morning of the triathlon and use the average of all the readings to determine the reservoir's temperature, Christen said.
Temperatures at the reservoir dropped between 73 degrees and 74 degrees several days ago, Christen said.
"With all the rain we've been getting, I'm guessing it dropped even further," he said.