Lucky Peak is considered a high-hazard dam.
"Does that frighten you?" asked Paul "Crash" Marusich, the mitigation specialist for Ada County Emergency Management.
"Well it shouldn't," he added. "High-hazard only means that we live beneath it. It's inspected regularly, it's monitored constantly and the dam is a quarter-mile wide at the base. The chances of it breaking are infinitesimal."
Marusich isn't going to say it's impossible, though.
"I'm just going to say getting struck by lightning twice while holding a winning lottery ticket is probably better than the chance of the dam breaking."
Regardless of how slight the chances, Ada County Emergency Management has a dam failure plan, as well as a 100-page flood response plan.
According to Marusich, the dam doesn't actually need to burst for the Treasure Valley to be in big trouble. There are three reservoirs situated above Boise and, when they get full around this time of year, they hold a collective 1 million acre feet of water.
"We are the closest community of our size to a dam in the nation," Marusich said. "Let's say the water is doing something called piping, where water is coming through in little spots. Crews are starting to repair it, but they have to relieve pressure on the dam by letting out the maximum amount of water they can, which is 25,000 cubic feet per second. We're already flooding town at that point."
The Boise River is flowing at around 2,000 cfs right now. At 25,000 cfs, Boise State University, Zoo Boise, Ann Morrison Park and most of Garden City would be flooded. If the dam is already letting as much water out as it can and the reservoir is still too full, it could lead to what Marusich called a "spillway event," which is when the water has to go somewhere—so it goes over the top.
"Without the dam failing, we're pushing 120,000 cfs through town," Marusich said. "Now, if the dam breached—because you would think maybe our agency actually looked at that—and the reservoirs were full, it would take somewhere between 50 minutes to two hours for the water to get to downtown Boise."
Marusich explained that when the water reached downtown, it would be 40 feet high, submerging just about every building lower than four stories.
"We're disaster nerds," he said. "We really are."