Chester Creek overflowed its banks Tuesday, sending cold water into the basements and crawl spaces of a handful of homes near Valley of the Moon Park.
The recent cold snap caused water to freeze from the bottom of the creek to the surface, said Jeff Urbanus, a city hydrologist.
With the bottom of the creek bed solid ice, water flowed over the banks in places, he said.
The phenomenon is caused by an uncommon confluence of weather events, he said. Cold air plus warm-season rains -- this is the second-wettest year for Anchorage on record -- made conditions ripe for the phenomenon called "anchor ice," Urbanus said.
"It is a bad problem, particularly when it's your house," he said.
Jen Clark, who lives in a split-level that backs up to the creek, knows firsthand.
Her daughter Amalie Clark went down to the basement Tuesday morning to clean out the litter box of Sarah, the family cat, when she stepped in 4 inches of water.
"There's water all over the basement! It's freezing!" Clark remembers her 6-year-old daughter yelling.
The floodwater covered all 1,500 square feet of the basement and soaked 10 cardboard boxes of books, vinyl records and a trampoline she was planning to give to Amalie and her twin brother, Jenson, for Christmas.
Clark enlisted the help of her 73-year-old mother-in-law, Conni Schlee, who swept water down a basement drain for more than eight hours.
Clark said the water started to recede at about 9:30 a.m., almost an hour after city crews started to work on the creek.
Urbanus said crews have been steaming holes in the ice, picking away at culverts and scooping chunks of ice out of the creek with backhoes, but that won't fix the flooding.
Almost 2 feet of ice fills the creek. With the overflow on top, the water level is more than twice its normal height, he said.
Fixing the flooding is deliberate process that has to be done in stages because if crews were to remove all the ice from the creek, the problem would only come back, he said.
Urbanus said it has been six or seven years since residents near the park have seen flooding caused by anchor ice.
Those who have had water in their crawl spaces and basements will have to wait for warmer weather for relief from floodwater, he said.
The ideal situation, he said, would be for the increase in temperatures to help break the ice, allowing the surface of the creek to freeze over.
"Warmer weather will cure the long-term problem," Urbanus said.
For now, Jen Clark and other flooded Valley of the Moon Park neighbors have a mess to clean up.
And this isn't the first time.
Clark's house, which is 16 feet from the middle of the creek, first flooded in January 2009, she said.
At that time, Clark said the basement was a living area complete with carpeting, furniture and a heating system, all of which was ruined by that flood.
Clark said she doesn't yet know if Tuesday's flood destroyed almost $10,000 in unfinished repairs from the damage in 2009.
"I have half a house I can't use," she said.
Clark sighed as the bottom of a cardboard boxes gave out and poured books into the water. One of the titles: Eugene O'Neill's "The Iceman Cometh."
Reach Benjamin Brasch at bbrasch@adn.com or 257-4349. Twitter: twitter.com/ben_brasch
By BENJAMIN S. BRASCH