Wendie Marriott and Bern Savikko’s Beach Road cabin was leveled by the December landslide. “It was smack dab in the middle of the slide,” Marriott said. Now “it’s a pile of boulders and tree stumps and mud and rock and debris… Everything is just gone.”

But Marriott, who lives mostly in Juneau, suspects a state law that hasn’t been invoked in three decades might entitle her and Savikko—and other Haines residents—to new land.

Marriott and…