A weekend Juneau jökulhlaup raised the water levels of Mendenhall Lake by several feet, but caused only minor interruptions to activities in the Mendenhall Valley.
The water level of Mendenhall Lake crested at just over 8.5 feet on Sunday night, less than 36 hours after it began rising from the glacial lake outburst flood of Suicide Basin, according to the National Weather Service. The flooding temporarily caused the closure of the Nugget Falls Trail and other trails at the Mendenhall Glacier Visitor Center, but not much else.
“It was one of the lower ones, but not saying there wasn’t enough storage in the basin,” NWS Senior Service Hydrologist Aaron Jacobs said.
All signs pointed to the lake reaching moderate flood stage, or 10 feet, when lake levels began rising on Saturday afternoon. However, the rate of flooding slowed about midway through the event.
“What we’re thinking that took place was the subglacial piping was not as efficient to let the basin drain (as) fast as it has in the past,” Jacobs said.
Mendenhall Lake has reached moderate flood stage in three of the last five years from the jökulhlaup —in 2014, 2016 and 2018, causing the inundation of the Mendenhall Campground, Skaters Cabin Road and the backyards of View Drive homes.
Tom Mattice, emergency programs manager for the City and Borough of Juneau, said he was caught off how quickly the jökulhlaup crested.
“It might have gotten a little bit into the campground, obviously it was flooded out to Nugget Falls, people couldn’t get to out to the Photo Point and that kind of stuff but other than that, I think it was fairly minimal,” Mattice said.
The lake level started to rise again Tuesday morning, but it’s not expected to reach as high as it did Sunday night.
The jökulhlaup arrived on the tail end of an 18-day drought, one of the longest stretches of dry weather in Juneau history.
• Contact sports reporter Nolin Ainsworth at 523-2272 or firstname.lastname@example.org. Follow Empire Sports on Twitter at @akempiresports.