Updated post — Dec. 6, 1:30 p.m.
Water levels at the Lower Ketchikan Lake Dam have fallen enough that officials no longer anticipate a risk of dam failure. Officials said Sunday morning that residents who evacuated low-lying areas near Ketchikan Creek over the weekend can now return to their homes.
That’s after the dam reached near-record levels Saturday evening.
It was the wettest week in a century in Ketchikan. And that’s saying something — Ketchikan is already among the wettest cities in the U.S.
Alaska climate researchers say nearly 20 inches of rain fell on the Southeast Alaska city between Nov. 29 and Dec. 5. Expand that to an eight-day window, and it’s almost two feet of rain.
All that water pushed a reservoir upstream of town to near-record levels — just over an inch shy of the all-time record set in 2015. And that concerned local officials enough to recommend that people living near the creek get to higher ground.
“So we have two areas that we’re concerned about. One is the actual dam. But more importantly, is the low lying places along the creek,” Ketchikan Public Utilities Electric Division Manager Andy Donato said Saturday evening. His agency maintains the Lower Ketchikan Lake Dam.
Three feet of water were flowing from an emergency spillway. Ketchikan Creek was ripping through town. The alert went out: parts of downtown and areas near the creek were told to evacuate. Officials stood up a shelter at the borough-owned recreation center.
Donato said he feared accumulating debris could flood low-lying areas.
“It doesn’t take much to start plugging that up. And then and then we can see flood conditions develop rapidly. So that’s our first concern,” Donato said Saturday.
But the larger concern was a possible dam failure. Ketchikan Emergency Manager Abner Hoage said that would mean widespread devastation.
“In a dam break scenario, which is the worst case scenario, that would be a 22,000 cubic-foot-per-second release. We have 115 residential structures, 43 commercial structures and seven government structures,” he said.
Officials warned that lake levels of 351 feet could damage the dam. Three feet higher, at 354 feet, and water would spill over the earthen top of the structure.
But as of noon Sunday, officials said it likely won’t get to that point anytime soon. Heavy rains have let up slightly. Utility crews ran the dam’s hydroelectric generators overnight to let water out from behind the structure. And the lake level crested at 350.1 feet shortly after 7 p.m. Saturday.
Officials lifted the voluntary evacuation Sunday morning. While they warned of minor street flooding, they said there was no immediate danger of dam failure.
But they said they’re standing by — and they say residents should stay alert, too.
Updated post — Dec. 5, 11:30 p.m.
Ketchikan’s emergency operations center says it does not anticipate forcing anyone to leave flood-prone areas — yet. Officials had previously predicted a mandatory evacuation overnight.
“I think our immediate danger from the potential to get to that critical level up at the dam has probably passed for the night,” Ketchikan’s emergency manager, Abner Hoage said late Saturday night.
“I would sleep with my ringer on. I would not put my earplugs in if I normally sleep with earplugs — just so that you can remain somewhat alert,” he said.
Officials continue to recommend that residents of low-lying areas near Ketchikan Creek evacuate to higher ground. They say the danger of flooding has not yet passed even as rainfall tapers off and the water level at Ketchikan Lake Dam begins to recede.
Hoage said rain is expected to pick up on Sunday.
“Probably another two inches between 6:00 a.m. and 3:00 p.m. So we’re going to be back up to the level we’re at now, if not even above that, before we get through the worst of the weather tomorrow,” he said.
Officials would use audible sirens to indicate a mandatory evacuation, and police officers would patrol with loudspeakers, local officials say. There would also be a mobile phone alert via the Nixle notification system.
Hoage says residents who have already evacuated should not return to their homes.
Hoage said at 10:45 p.m. Saturday the water level at Ketchikan Lake Dam has dropped slightly in the past few hours. As of 10:00 p.m., the lake was below 350 feet and falling.
For context, officials warn that levels about 351 feet could damage the dam. Levels above 354 feet could lead to more serious damage and threaten failure.
“By doing what we call the voluntary evacuation, it raises people’s attention. And it gives them more time to respond,” Hoage said. He said a mandatory evacuation would be issued if there was a more imminent threat.
An evacuation shelter is set up at Ketchikan’s Gateway Recreation Center at 601 Schoenbar Road for those with nowhere else to go. But officials ask that residents first seek shelter with friends and family outside the evacuation zone.
Local officials say there’s only one road closure for now. That’s Freeman Street. Other roads are open to through traffic, including Stedman Street at the mouth of Ketchikan Creek. That’s the primary road connection between northern and southern parts of Ketchikan’s road system.
Updated post — Dec. 5, 8:30 p.m.
Officials say they’re on the cusp of issuing a mandatory evacuation order for residents in low-lying areas along Ketchikan Creek. First responders are going door-to-door asking Ketchikan residents in these areas to pack a bag and be prepared to be displaced for two to three days.
Ketchikan Public Utilities Electric Division Manager Andy Donato says the danger of an uncontrolled dam release is very real.
As of 7:00 p.m. Saturday officials confirmed a mandatory evacuation order would be issued in the next few hours.
“I’m going to say 100% probable,” Donato said.
That’s as Ketchikan Lakes Dam reached “moderate flood stage” Wednesday. Officials said in a statement that “conditions are developing that could cause a breach and failure of the Ketchikan Lakes dam by 3:00 a.m. Sunday morning.”
Emergency Manager Abner Hoage said there’s not an imminent risk of the dam failing as of 7:00 p.m. Saturday.
But officials say that as the lake approaches record levels, they’re advising people to prepare for the worst.
“So we have two areas that we’re concerned about. One is the actual dam. But more importantly, is the low lying places along the creek,” said Ketchikan Public Utilities Electric Division Manager Andy Donato, whose agency maintains the Ketchikan Lakes Dam upstream from downtown.
Right now, officials are most concerned about flooding along Ketchikan Creek. Areas along the creek have been asked to evacuate.
Donato says he’s concerned that flood-driven debris, like downed trees, could pile up under bridges or in narrow sections of the creek.
“It doesn’t take much to start plugging that up. And then and then we can see flood conditions develop rapidly. So that’s our first concern,” he said.
But the longer-term concern is the integrity of the dam. Donato says that water is expected to rise above a reinforced section of the dam by 3:00 a.m. Sunday morning, and that could lead to erosion. That would be at a lake elevation of 351 feet.
“At 351.0, structurally, we come up to something different in the interior of the dam, the dam that’s up there is an earthen dam, built on some old wooden cribs, and we start exceeding the internal cribbing,” Donato said.
The National Weather Service reported that the level was roughly 13 inches below that mark at 6:00 p.m. Saturday.
High lake levels is one of a few factors that could trigger a mandatory evacuation for low-lying areas near the creek. Hoage, the emergency manager, said that included a total of 28 residences and 25 commercial buildings.
Damage to the dam could also prompt mandatory evacuations.
Donato says he’s not quite sure when residents will be ordered to leave, but he anticipates evacuations being called this evening. He says plans are in flux as conditions on the ground change. But he says he’s sure an order will be issued Saturday.
Officials say they’ll activate audible sirens when a mandatory evacuation is issued. Police officers will also patrol with loudspeakers.
One reason an evacuation could be called earlier is the simple fact that it’s easier to get people to leave before they head to bed, Donato said.
Another major milestone would be reached at 354 feet, Donato said. That’s the height of the dam. And if water starts flowing uncontrolled over the top of the dam, that could lead to erosion, allowing larger and larger flows out of the dam, and potentially a dam failure.
Hoage says that could be devastating.
“In a dam break scenario, which is the worst case scenario, that would be at 22,000 cubic foot per second release. We have 115 residential structures, 43 commercial structures and seven government structures.”
Hoage says those in the evacuation zone should get to higher ground immediately.
“If it does get there, and if things were to go bad, and we were to have some sort of erosion or, you know, dam couldn’t hold that the weight of the water because you’re adding exponentially more water, the higher up it gets in that reservoir,” he said. “Then you get a crack, or whatever — an earthquake hits at the wrong time — and the water comes through for whatever reason.”
“That’s what we’re worried about the potential for,” he said.
The weather service expects another half inch overnight. Forecasters say they’re expecting another two inches during daylight hours Sunday and another half inch Sunday night. Rain is forecast to let up slightly by Monday with less than an inch expected.
Original post — Dec. 5, 7:00 p.m.
Local officials are asking residents of low-lying areas along Ketchikan Creek to immediately evacuate to higher ground. First responders are going door-to-door asking residents to pack a bag and evacuate for an anticipated 48-72 hours.
Ketchikan’s emergency operations center warned Saturday evening that rising water “could cause a breach and failure of the Ketchikan Lakes Dam by 3:00 a.m. Sunday morning.”
Officials are recommending evacuations of the following areas:
- Downtown Ketchikan east of Bawden Street, including areas of Mission Street, Dock Street and all of Creek Street.
- Stedman Street from Chief Johnson Totem Pole to the Salvation Army.
- All residents along Park Avenue and nearby streets.
- Schoenbar Road from Valley Forge Road to the ballfields.
- Woodland Avenue.
- Deermount Street north of Woodland Avenue.
- Harris Street.
- Freeman Street.
At this point, they say the downtown Mary Frances Condos are not at risk of flooding.
An evacuation shelter has been set up at Ketchikan’s Gateway Recreation Center at 601 Schoenbar Road for those without somewhere else to go — but local officials are asking folks who are able to evacuate to friends’ and families’ homes outside the evacuation zone.
Officials say some limited space is available for pets at Ketchikan’s animal shelter. Island to Island Vet Clinic also has announced on Facebook that they have some space available to shelter pets for those who must evacuate.
Local officials say they anticipate upgrading the voluntary evacuation to a mandatory order.
A bus is circulating through the evacuation area along Park Avenue, Bawden Street and Stedman Street.
This is a breaking story. Check back for updates.
