Update posted at 5:35 p.m., Thursday, July 21: An official with the Juneau National Weather Service office said flooding from Mendenhall Lake and River will begin to recede very quickly.
Aaron Jacobs, general forecaster and hydro focal points specialist with the local National Weather Service Office, said floodwaters are going to recede very quickly.
“It should be below flood stage (by 8 p.m.)," said Aaron Jacobs, general forecaster and hydro focal points specialist for the weather service. "Everything is calming down as the lake has drained and the amount of water input is slowing. There is some (input), but its not as much.”
Tom Mattice, city emergency coordinator, urged people to stay away from river banks for a while since the banks are soft and were undercut in the flooding.
Update posted at 4:16 p.m., Thursday, July 21: View Drive has reopened, according to a release from the City and Borough of Juneau.
Update posted at 4:05 p.m., Thursday, July 21: A National Oceanic and Atmospheric Administration meterologist from the Juneau office said water levels are receding in both Mendenhall Lake and River.
Tim Steffens said a pond of water on top of the glacier drained into the glacier because a dam collapsed. He said a colleague has flown up to the glacier a couple times, but he did not know how big the pond had been.
Steffens said there is a remote chance that a piece of ice could have lodged and plugged up the flow and that it could start again, however, that chance is small. He said they largely expect the event to be finished and expect to continue to see receding flood waters.
Update posted at 3:23 p.m., Thursday, July 21: Both Mendenhall Lake and River have crested and flood waters are receding, according to a release from the National Weather Service.
Mendenhall River crested at 13.07 feet at 11:15 a.m. Thursday, and was down to 12.90 feet at 1:30 p.m. the release states. Meanwhile, the lake topped out at 10.93 feet at noon Thursday, and was down to 10.47 feet by 2:15 p.m.
However, both bodies of water are still above the flood stage and the flood warning will remain in effect until 10 p.m. Thursday.
Update posted at 1:53 p.m., Thursday, July 21: The water level at the Mendehall Glacier Visitor Center appears to be receeding, albeit slowly.
The water was about two inches from the top of the walkway leading to Photo Point at its highest, said Ron Marvin, manager of the Mendenhall Glacier Visitor Center. He said that the water was down about an inch from that level at about 1:45 p.m.
Update posted at 1:24 p.m., Thursday, July 21: City Manager Rod Swope, members of the Juneau Police Department and the city's Public Works department are driving through neighborhoods in the Mendenhall Valley to see if the flooding has spread, though there is no indication that it has.
Swope strongly advised people to abandon recreation plans on the Mendenhall River until the flooding passes. However, he did say the city does not have the power to actually prevent people from entering the river.
"Somebody would be quite foolish to get into the river right now," he said.
Update posted at 11:27 a.m., Thursday, July 21: Officials are currently conducting a fly-over of the Mendenhall Glacier to determine which glacial lake burst and to estimate how much water is left.
Tom Mattice, City and Borough of Juneau emergency coordinator, stated they have a rough idea of what lake it is but cannot confirm exactly which one at this time.
He stated there is standing water on View Drive. That area is currently under a soft closure, meaning homeowners are advised to leave, but evacuation of residences is not mandatory. He confirmed the Mendenhall Campground is closed.
“We’re warning people about trails along the river,” he said. “Cutbanks are extremely unstable.”
Mattice said this type of flooding is common on rivers like the Taku, but the occurrence is a rarity in the Mendenhall River.
At this time, he said, water is the river is approaching historical levels.
“I’ve talked to people who say they’ve never seen river levels this high,” he said. “And I’ve talked to others who say they haven’t seen it this high in 30 years.”
Update posted at 11:16 a.m., Thursday, July 21: The City and Borough of Juneau has announced the noon closure of the Kaxdigoowu Heen Dei (Brotherhood Bridge Trail), between Glacier Highway and River Road, until further notice.
CBJ asks people to stay away from the Mendenhall River banks as they are unstable. Do not stop to take pictures from the bridges.
Update posted at 10:20 a.m., Thursday, July 21: The NWS has now extended the flood warning to 10 p.m. Thursday night for the areas of Mendenhall Lake and the Mendenhall River.
A resident of View Drive stated they cut power to their riverside residence as a precaution and have since chosen to leave the area.
The NWS states levels of the river and lake currently continue to rise "at a significant rate."
Update posted at 10:06 a.m., Thursday, July 21: A spokesperson at the City & Borough of Juneau Emergency Programs Office stated they cannot confirm whether or not View Drive will be flooded later this afternoon. It was also stated they could not confirm whether or not individuals will be evacuated from areas affected by flooding.
The spokesperson stated responders are currently in the field working to establish the scope of the flooding in order to make the best choices for residents.
Update posted at 9:50 a.m., Thursday, July 21: The National Weather Service has confirmed the flooding is due to a glacial lake outburst at an unknown location and of an unknown size. The flood warning is currently still in effect for the Mendenhall Lake and river areas.
The NWS states they do not know how much more water in these areas will rise, but visual reports indicate levels will continue to rise through the evening.
A release states flood waters will continue to impact the Skaters Cabin spur road, Mendenhall Campground and areas of View Drive. U.S. Forest Service rangers have closed the Mendenhall Campground along with the road leading to the West Glacier trailhead. Officials anticipate that View Drive will be flooded by early afternoon.
Locals are reminded to stay away from the area. Officials would like to remind those observing the event to be aware that high volumes of water can deteriorate river banks, rendering them unstable.
Update posted at 7:13 a.m., Thursday, July 21: The National Weather Service has elevated the initial flood advisory to warning status Thursday morning for the Mendenhall Lake and Mendenhall River areas.
A statement on the organization's website states, as of 5:15 a.m. Thursday, the lake was just below moderate flood stage of 10 feet. Mendenhall River is also flowing just below moderate flood stage of 12.5 feet at 4:45 a.m., according to the statement.
NWS stated water levels on the lake have been rising at a rate of about 2 inches per hour for the past 12 hours.
Currently, the flood warning remains in effect until noon Thursday.
"An important thing to note is that it is uncertain how high the water will get with this event since it is a first-time occurence," the NWS stated on its website. "It is not known where the exact source of the release is and how much water is being released from it."
A flood warning means that flooding is imminent or has been reported. The organization stated river rise will be slow and flash flooding is not expected, however, interested parties should take necessary precautions such as remaining cautious in low-lying areas and report any flooding to law enforcement. Those agencies will report to the NWS forecast office in Juneau.
Stay updated on this event. Check back for updates.
The National Weather Service has issued a flood advisory for the Mendenhall Lake and Mendenhall River areas.
The water levels in the lake and river have risen more than two feet since Tuesday afternoon, the warning states. The cause may be a glacial dammed lake, the release states.
The water level is currently rising 1-2 inches per hour, and, at that rate, the lake will hit its flood stage of nine feet by midnight tonight. The river’s flood stage is 11.5 feet, though the warning does not state when the weather service believes the water level will it this mark, or even if it will.
When Mendenhall Lake floods, water will begin to cover the road between Skaters Cabin and the West Glacier Trailhead. If the river floods, areas along View Drive will begin to see minor flooding.
People living near the river are advised to stay alert and be ready to take action. The cold water can cause hypothermia.
The warning is set to expire at 6 a.m. Thursday.