Homeowners warned of flood risk as lake starts to break through ice dam
On Tuesday morning, they confirmed water had started escaping the ice dam and flowing downstream, with flooding expected from late on Tuesday into Wednesday.
Flooding from the basin has become an annual concern and, in recent years, has swept away houses and swamped hundreds of homes.
Government agencies installed a temporary levy this year in hopes of guarding against widespread damage.
'This will be a new record, based on all of the information that we have,' Nicole Ferrin, a National Weather Service meteorologist, told a news conference on Tuesday.
The Mendenhall glacier, a thinning, retreating glacier that is a major tourist attraction in south-east Alaska, acts as a dam for Suicide Basin, which fills each spring and summer with rainwater and snowmelt.
The basin itself was left behind when a smaller glacier nearby retreated.
When the water in the basin builds up enough pressure, it forces its way under or around the ice dam, entering Mendenhall Lake and eventually the Mendenhall River.
Before the basin reached the limit of its capacity and began overtopping over the weekend, the water level was rising rapidly – as much as 1.22 metres per day during especially sunny or rainy days, according to the National Weather Service.
The threat of so-called glacier outburst flooding has troubled parts of Juneau since 2011. In some years, there has been limited flooding of streets or properties near the lake or river.
But 2023 and 2024 marked successive years of record flooding, with the river last August cresting at 4.9m – 30cm over the prior record set a year earlier, and flooding extending farther into the Mendenhall Valley.
This year's flooding was predicted to crest at between 4.96m and 5.12m.
Last year, nearly 300 residences were damaged.
A large outburst can release some 15 billion gallons of water, according to the University of Alaska Southeast and Alaska Climate Adaptation Science Centre.
That's the equivalent of nearly 23,000 Olympic-size swimming pools. During last year's flood, the flow rate in the rushing Mendenhall River was about half that of Niagara Falls, the researchers said.
City officials responded to concerns from property owners this year by working with state, federal and tribal entities to install a temporary levee along roughly 2.5 miles of riverbank in an attempt to guard against widespread flooding.
The installation of about 10,000 1.2m barriers is intended to protect more than 460 properties from flood levels similar to last year, said Nate Rumsey, deputy director with the city's engineering and public works department.
The US army corps of engineers is at the start of what is expected to be a years-long process of studying conditions in the region and examining options for a more permanent solution.
The timeline has angered some residents, who say it is unreasonable.
Outburst floods are expected to continue as long as the Mendenhall Glacier acts as an ice dam to seal off the basin, which could span another 25-60 years, according to the university and science centre researchers.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
The Guardian
a day ago
- The Guardian
More than 400 people suspected to have died from extreme heat in Arizona county
More than 400 people are suspected to have died from extreme heat in Maricopa county, Arizona, so far this summer, according to official figures, as the brutal current heatwave enters its 12th day. August is on track to be the hottest on record, with temperatures hitting at least 110F (43C) every day apart from one so far. As of 11 August, at least three daily records had been broken including an all-time monthly high of 118F (48C), as well as several night-time record temperatures, according to Isaac Smith, meteorologist at the National Weather Service (NWS) in Phoenix. The current extreme heat warning issued by the NWS is the fourth and longest of the summer thus far, and will extend at least through Wednesday night with temperatures forecast to hit 110F. Increased cloud cover and possible thunderstorms will then bring a brief respite towards the weekend but another very hot spell is forecast by the start of next week. Maricopa county is home to Phoenix, the fifth largest and hottest major US city, as well as several smaller urban hubs dotted amid the Sonora desert including Scottsdale, Tempe and Mesa. Midway through the hot season, the current official death count – including suspected and confirmed heat-related fatalities – is about 30% lower than this time last year, the second deadliest on record. In 2025, the county medical examiner's office has so far confirmed only 35 heat deaths – 17 directly caused by exposure to high temperatures, and 18 cases where heat contributed to the fatality, including by exacerbating chronic medical conditions or the effects of alcohol or methamphetamine. Another 369 suspected heat-related deaths remain under investigation, according to the county's heat surveillance dashboard which is updated weekly. June and July were a little cooler than recent years, despite topping 115F on multiple days, which at least partially explains the lower death toll. Improved access and extended hours at city cooling centres may also be playing a role, according to Dr Nick Staab, the county's chief medical officer. First responders and hospitals have reportedly gotten better at treating heatstroke and other temperature-related emergencies. Yet despite the encouraging numbers, Maricopa county is still on track to be the deadliest place for heat in the US after New York City, the country's largest metropolis, where heat contributes to 525 deaths on average each year. 'With this many cases still under investigation and it only being mid-August, there's a lot that could still happen,' Staab told KJZZ, the local public radio station. Heat-related deaths have soared in Maricopa county over the past decade, with 645 in 2023 compared to 61 in 2014. The county has become increasingly unlivable for many amid record-breaking heatwaves driven by the global climate crisis, unchecked urban sprawl and an affordable housing crisis – which combined with patchy mental health and substance misuse services has contributed to a growing unsheltered population. Last year, heat deaths fell for the first time in a decade to 608, according to official figures, but the city and county have since come under fire for alleged undercounting. A recent investigation by the local TV station ABC15 identified multiple cases in which heat was discounted as a factor despite the person dying in extreme temperatures. 'People are dying awful, preventable deaths that are not being accounted for in the official figures. We need more consistency and transparency if we're going to wrap solutions around this public health crisis,' said Stacey Champion, a community advocate campaigning for more standardized counting of heat-related deaths in Arizona. Neither the city nor the county responded immediately to questions surrounding the official death toll. Heat is the deadliest weather phenomenon. But every heat death is preventable, and often indicates a lack of access to adequate shelter, cooling and/or health, addiction and social services. So far this year, three-quarters of heat-related deaths have occurred outside, where temperatures in the most built-up, least shady parts of Phoenix can be 20 or 30F higher on the sidewalk than the NWS's airport weather station. Unhoused people account for 40% of deaths, while substance misuse contributed to two-thirds. June was the 11th warmest on record, and July the ninth hottest. The city, county and state have sought to tackle the increasingly unlivable summer environment through tree canopy initiatives, cooling technologies and an expansion of cooling centres among other policies – in part with the help of Biden-era programs and funds. But there is little or no hope of ongoing federal support under the Trump administration, which is dismantling environmental justice programs, climate change research and mitigation efforts, as well as access to healthcare, food stamps (Snap) and other social safety nets. Currently one in four heat deaths in the county occur indoors, and energy costs are predicted to rise significantly under Trump which risks making Maricopa county and beyond even more deadly as summers get hotter. Meanwhile firefighters are struggling to control at least five major wildfires across the state, which have so far burnt about 180,000 acres. Hot, dry and windy conditions are fuelling the flames in Arizona – as well as fires in California, Utah, Colorado and large swathes of Canada.
The Guardian
2 days ago
- The Guardian
More than 400 people suspected to have died from extreme heat in Arizona county
More than 400 people are suspected to have died from extreme heat in Maricopa county, Arizona so far this summer, according to official figures, as the brutal current heat wave enters its 12th day. August is on track to be the hottest on record, with temperatures hitting at least 110F (43C) every day apart from one so far. As of 11 August, at least three daily records had been broken including an all-time monthly high of 118F (48C), as well as several nighttime record temperatures, according to Isaac Smith, meteorologist at the National Weather Service (NWS) in Phoenix. The current extreme heat warning issued by the NWS is the fourth and longest of the summer thus far, and will extend at least through Wednesday night with temperatures forecast to hit 110F (43C). Increased cloud cover and possible thunderstorms will then bring a brief respite towards the weekend but another very hot spell is forecast by the start of next week. Maricopa county is home to Phoenix, the fifth largest and hottest major US city, as well as several smaller urban hubs dotted amid the Sonora desert including Scottsdale, Tempe and Mesa. Midway through the hot season, the current official death count – including suspected and confirmed heat-related fatalities – is around 30% lower than this time last year, the second deadliest on record. In 2025, the county medical examiner's office has so far confirmed only 35 heat deaths – 17 directly caused by exposure to high temperatures, and 18 cases where heat contributed to the fatality, including by exacerbating chronic medical conditions or the effects of alcohol or methamphetamine. Another 369 suspected heat-related deaths remain under investigation, according to the county's heat surveillance dashboard which is updated weekly. June and July were a little cooler than recent years, despite topping 115F (46C) on multiple days, which at least partially explains the lower death toll. Improved access and extended hours at city cooling centres may also be playing a role, according to Dr Nick Staab, the county's chief medical officer. First responders and hospitals have reportedly gotten better at treating heat stroke and other related temperature related emergencies. Yet despite the encouraging numbers, Maricopa county is still on track to be the deadliest place for heat in the US after New York City, the country's largest metropolis, where heat contributes to 525 deaths on average each year. 'With this many cases still under investigation and it only being mid-August, there's a lot that could still happen,' Staab told KJZZ, the local public radio station. Heat-related deaths have skyrocketed in Maricopa county over the past decade, with 645 in 2023 compared to 61 in 2014. The county has become increasingly unlivable for many amid record breaking heatwaves driven by the global climate crisis, unchecked urban sprawl and an affordable housing crisis – which combined with patchy mental health and substance misuse services has contributed to a growing unsheltered population. Last year, heat deaths fell for the first time in a decade to 608, according to official figures, but the city and county have since come under fire for alleged undercounting. A recent investigation by local TV station ABC15 identified multiple cases where heat was discounted as a factor despite the person dying in extreme temperatures. 'People are dying awful, preventable deaths that are not being accounted for in the official figures. We need more consistency and transparency if we're going to wrap solutions around this public health crisis,' said Stacey Champion, community advocate campaigning for more standardized counting of heat-related deaths in Arizona. Neither the city nor the county responded immediately to questions surrounding the official death toll. Heat is the deadliest weather phenomena. But every heat death is preventable, and often indicates a lack of access to adequate shelter, cooling and/or health, addiction and social services. So far this year, three quarters of heat related deaths have occurred outside, where temperatures in the most built-up, least shadiest parts of Phoenix can be 20 or 30F higher on the sidewalk than the NWS's airport weather station. Unhoused people account for 40% of deaths, while substance misuse contributed to two thirds. June was the 11th warmest on record, and July the ninth hottest. The city, county and state have sought to tackle the increasingly unlivable summer environment through tree canopy initiatives, cooling technologies and an expansion of cooling centres among other policies – in part with the help of Biden-era programs and funds. But there is little or no hope of ongoing federal support under the Trump administration, which is dismantling environmental justice programs, climate change research and mitigation efforts, as well as access to healthcare, food stamps and other social safety nets. Currently one in four heat deaths in the county occur indoors, and energy costs are predicted to rise significantly under Trump which risks making Maricopa county and beyond even more deadly as summers get hotter. Meanwhile firefighters are struggling to control at least five major active wildfires across the state, which have so far burnt around 180,000 acres. Hot, dry and windy conditions are fueling the flames in Arizona – as well as fires in California, Utah, Colorado and large swathes of Canada.
BBC News
2 days ago
- BBC News
Evacuations in Alaska after glacial melt raises fears of record flooding in Juneau
Some Alaskans are evacuating their homes as meltwater escapes a basin dammed by the Mendenhall Glacier - raising fears of record-breaking flooding in the US state's capital city. The National Weather Service (NWS) office in Juneau has issued a flood warning as glacial outburst water flows into Mendenhall River, putting homes in the area at risk. For days, local officials have warned residents they may be forced to evacuate. On Tuesday, they confirmed water had begun escaping the ice dam and flooding was expected in the coming days. The glacier, a popular tourist attraction, is 12 miles (19km) from Juneau. Water levels reached 9.85ft (3m) on Tuesday, below major flooding levels which begin at 14ft, the NWS said. But by Wednesday morning they were above 16ft, which is considered a crest. "This will be a new record, based on all of the information that we have," Nicole Ferrin, a weather service meteorologist, said at a press conference on Tuesday. The Juneau city website explains that glacial lake outbursts happen when a lake of melting snow and ice and rain drains rapidly. It compares the process to pulling out a plug from a full bathtub. When meltwaters reach a certain level, they can overtop a glacier that previously held them Governor Mike Dunleavy issued a state disaster declaration on Sunday because of the "imminent threat of catastrophic flooding from a glacier lake outburst flood (GLOF)" in the Juneau has been an annual concern in the area since 2011, as homes have been damaged and swept away by deluges. Last year, hundreds of residences were damaged.
