Update: Mendenhall River to crest at about 16.6 feet between ‘morning to midday’ Wednesday

Few people staying at emergency shelter as of 10 p.m. despite forecast of flood waters peaking hours earlier than originally predicted

The Mendenhall River at 10 p.m. Tuesday, Aug. 12, 2025. The National Weather Service reported the river level at about 13 feet at the time — a foot below major flood stage — and it is expected to crest at between 16.25 and 16.75 by midday Wednesday. (Ellie Ruel / Juneau Independent)

This is a developing story.

By Mark Sabbatini and Jasz Garrett

Juneau Independent

Update 11 p.m.: An updated forecast just before 10 p.m. Tuesday put the level of the Mendenhall River at about 13 feet — a foot below major flood stage — and the water is expected to crest "around Wednesday morning to midday" at a record level between 16.25 and 16.75 feet.

Emergency officials earlier during the evening urged residents in flood inundation areas to evacuate their homes promptly — rather than wait until morning — due to the crest period shifting from the original prediction of late Wednesday afternoon to earlier during the day.

But as of 10 p.m. only one person was in the gym at the Floyd Dryden school building set up as an emergency shelter, said Jay Kurtz, regional disaster director for the American Red Cross of Alaska. A few more people were in RVs and other vehicles in the parking lot, and a few more people told shelter workers earlier during the evening they planned to return to stay overnight.

The parking lot at Floyd Dryden school remains mostly empty at about 10 p.m. Tuesday, Aug. 12, 2025, with few people living in flood zone areas opting to use the site as the designated emergency overnight shelter set up by city and other emergency officials. (Mark Sabbatini / Juneau Independent)

Update 7:30 p.m.: Record flooding of the Mendenhall River is expected to peak between 8 a.m. and noon Wednesday, according to a forecast by the National Weather Service Juneau as of about 6:45 p.m. Tuesday.

The crest is hours earlier than a forecast posted at 5 p.m. Tuesday, calling for the crest to occur between 4 and 6 p.m. Wednesday.

"The reason for the change (in) crest timing is due to rain masking the start of the subglacial release and refining the initial start time of the event," a flood alert published by the weather service states.

Andy Park, a meteorologist with National Weather Service Juneau, said their staff is monitoring the Mendenhall Lake gauge. The forecasted crest time depends on the rate of rise of the lake gauge.

"Right now, we're just watching the rate of rise on the Mendenhall Lake and making sure our forecast matches that," he said. "So that's why you have such a large window. We're not going to say the river is going to crest exactly at this time right now."

A graph shows the forecast height of the Mendenhall River from a glacial outburst flood that occurred Tuesday morning, with a record crest of 16.6 feet predicted by Wednesday afternoon. (National Weather Service Juneau)

An observation of the lake gauge was 12.02 feet at 7:15 p.m. As of about 7:40 p.m., Park said the rate of rise was about four inches an hour. The weather service will continue monitoring the flood throughout the night.

"We've got a lot of eyes on this thing," he said.

The City and Borough of Juneau is continuing to recommend evacuations for residents in the 17-foot flood inundation zone. An emergency shelter is available at Floyd Dryden Middle School.

Update 6 p.m.: An updated forecast at 5 p.m. Tuesday calls for the Mendenhall River to crest between 16.25 feet and 16.75 feet sometime between 4 and 6 p.m. Wednesday, according to the National Weather Service.

"Water levels will go below major flood stage around Wednesday night," the alert notes, referring to a river level of 14 feet.

The river was at 11.5 feet at 6 p.m. Tuesday, according to the official Suicide Basin website.

Some closures and mandatory evacuations have already occurred, including Mendenhall Campground and CBJ facilities in the vicinity of Dimond Park. Officials also say residents not living in flood zone neighborhoods should avoid those areas and checks of people trying to enter will be made as conditions get more severe.

The Mendenhall Back Loop Bridge is scheduled to close at 7:30 p.m. Tuesday and remain closed until the river drops below 12 feet, according to the Alaska Department of Transportation and Public Facilities. The department also stated an FAA Temporary Flight Restriction (TFR) — banning items including drones — is in effect over the Mendenhall River in the flood zone from 8 p.m. Tuesday to 8 p.m. next Tuesday, Aug. 19.

Original story 10:45 a.m.: A glacial lake outburst flood from Suicide Basin has occurred and flooding of the Mendenhall River is expected to crest at about 16.6 feet Wednesday afternoon, but could peak by late morning, according to city and weather officials.

"This will be a new record based on all of the information that we have," said Nicole Ferrin, a warning coordination meteorologist for the National Weather Service Juneau, during a press briefing Wednesday morning.

The release occurred at 9:21 a.m. Tuesday, according to a flood warning issued by the weather service. The Mendenhall River reached the moderate flood stage of 10 feet at about 12:30 p.m. and could surpass the major flood stage of 14 feet by 7 a.m. Wednesday, said Jeff Garmon, meteorologist in charge at the station.

Peak flooding could occur anytime between late morning and mid-afternoon Wednesday, he said. But because the timing of that isn’t certain, residents in affected areas shouldn’t be making plans based on a specific crest time.

"Basically, everybody needs to be where they need to be moved to by early tomorrow morning," he said.

Once the river reaches the major flood stage of 14 feet, the final rise could occur within a two- to four-hour period, Garmon said.

One reason predicting the timing of the flood’s crest — which at present is sooner than the 4 p.m. original time forecast when the release occurred — is heavy rain during the previous days, which was not a factor during record flooding last year, according to Garmon.

"We have not had rainfall conflicting the data like we have over the past 24 hours," he said.

Ferrin said a crest between 16.3 to 16.8 feet is probable, with the middle figure of 16.6 feet as the official estimate, and a reassessment of that level may occur once 24 hours have passed since the start of the outburst flood.

Graham Chaytors, environmental services director for Riverview Senior Living, and Jacob Pickard, dietary director for the center, set up cots provided by the American Red Cross in a fellowship hall on the grounds of St. Paul’s Catholic Church on Tuesday, Aug. 12, 2025. A total of 26 residents at the senior center are expected to use the hall space as an emergency shelter during a glacial lake outburst flood expected to peak Wednesday afternoon. (Laurie Craig / Juneau Independent)

Officials during the briefing emphasized people who do not live in flood zone areas should avoid the area and noted live footage of the river from multiple cameras is at bit.ly/JuneauFloodReady. Sam Russell, assistant fire chief for Capital City Fire/Rescue, said there have been instances of people climbing onto the levee of HESCO barriers installed to protect neighborhoods, and "they're not designed for that."

Street and road closures are also planned, Russell said.

"As we start closing areas due to the evacuation, we're going to have personnel that will be asking for name and information, and discouraging folks from getting back into those areas," he said. "If you don't have homes back in the areas, we're going to ask that everybody stay out of those areas for your safety. And then even those that do have homes that are back in the areas, personnel are going to ask you ‘Where do you live? What's your phone number? Give me your name.’ And we're doing that for your safety in case there is an event where someone gets lost (so) we've got a record that they went back into those areas (and) we might be able to find them more easily."

An emergency evacuation shelter will be open at Floyd Dryden Middle School Gymnasium by Tuesday afternoon, according to officials at the briefing. A notice sent by CBJ states parking is limited, so people in flood areas not staying at the shelter should park their vehicles at St. Brendan’s Episcopal Church at 4207 Mendenhall Loop Road, Shepherd of the Valley Lutheran Church at 8198 Keegan Street, Christ Lutheran Church at 10300 Glacier Highway or Juneau Christian Center at 8001 Glacier Highway.

Sabrina Grubitz, left, public safety manager for the Central Council of the Tlingit and Haida Indian Tribes of Alaska, and Ryan O’Shaughnessy, emergency programs manager for the City and Borough of Juneau, discuss flood preparation measures during a briefing at the Juneau Police Department station on Tuesday, Aug. 12, 2025. (Laurie Craig / Juneau Independent)

Alaska Electric Light and Power announced shortly before 10 a.m. that, "Due to the flood announcement from CBJ, we are preemptively disconnecting service to the Mendenhall Campground. We will continue to provide outage updates throughout the flood event."

CBJ Emergency Programs Manager Ryan O'Shaughnessy said public services such as electricity to neighborhoods will be monitored once the river begins posing a threat.

"They do not plan to immediately cut power for the neighborhood that is behind the HESCO barriers," he said during a press briefing Monday. "If we do start to see inundation in that neighborhood, power will be cut immediately to the entire neighborhood and then turned back on in phases starting from the intersection of Mendenhall and Steven Richards, and sort of work its way back up through the neighborhood."

Water and sewer services should not be impacted, O'Shaughnessy said.

Juneau School District Superintendent Frank Hauser said during a media briefing Tuesday a decision about school closures for Thursday — the first scheduled day of the school year — will be made by noon Wednesday. If it is necessary to close any schools for flood-related reasons, then all district schools will be closed, he said.

"Kax̲dig̲oowu Héen Elementary School, Thunder Mountain Middle School, and Mendenhall River Community School are in the evacuation advisory area," a subsequent notice posted at the district’s website states. "These locations will close at 4:00 p.m. on Tuesday, August 12, and will remain closed until flood waters recede and the ‘All Clear’ is issued by the City and Borough of Juneau." Also, all extracurricular activities and school-sponsored events at all schools are canceled Tuesday and Wednesday, as is the Freshman First event at Juneau-Douglas High School: Yadaa.at Kalé.

Juneau Animal Rescue, in a social media message, stated shelter spots for pets "are limited and available on a first-come, first-served basis" during business hours from 9:30 a.m. to 5:30 p.m.

"We’re starting to fill up quickly, so don’t wait, act now to ensure your furry family members have a safe place," the message states. Fees are $5 a day per cat, $15 a day per dog. and "if your pet is unvaccinated/unlicensed, we will provide that for additional fees."

The U.S. Coast Guard issued an advisory stating, "due to flood conditions on the Mendenhall River, mariners transiting in the vicinity of Fritz Cove, Auke Bay, North Douglas Island, Spuhn Island, and surrounding areas are advised that additional debris may be present in these areas. Mariners are advised to use caution."

Last year’s record flood that damaged nearly 300 homes crested at 15.99 feet. However, a semipermanent levee of HESCO barriers built since then is intended to protect homes even if water levels reach 18 feet.

An emergency alert about a glacial lake outburst flood occurring at Suicide Basin is issued at about 9:30 a.m. Tuesday. (City and Borough of Juneau)

Evacuation and other flood information is available at the Juneau Glacial Flood Dashboard. A notice published on CBJ’s Facebook page advises residents in the 17-foot inundation zone "evacuate the area until the flood waters recede and an ‘All Clear’ message is sent via the Wireless Emergency Alert system and/or CBJ Alerts."

Advisories issued by CBJ also note:

• To shelter evacuated pets, contact Juneau Animal Rescue at (907) 789-6997. The Red Cross is not able to accommodate pets at Floyd Dryden.

• Evacuation routes intended to avoid congestion and road or bridge closures are noted at https://juneau.org/.../suicide-basin-outburst-underway...

• CBJ facilities along the Mendenhall River, including the Mendenhall Valley Public Library, Dimond Park Field House, Dimond Park Aquatic Center, and all nearby fields (Dimond Park, Melvin Park, Mendenhall River) will close at noon Tuesday and remain closed all day Wednesday due to projected flooding.

• The Flood Information Hotline is live at (907) 500-0890 for non-emergency questions. Emergency reports should be made to 911.

• Sign up for emergency alerts by visiting bit.ly/CBJAlerts or texting CBJ to 38276.

• Contact Mark Sabbatini at editor@juneauindependent.com or (907) 957-2306. Contact Jasz Garrett at jasz@juneauindependent.com or (907) 723-9356.