A sunny summer Sunday found Iditarod rookie Mary Helwig reading a book on her lawn near Willow when a neighbor’s text interrupted: A fast-moving forest fire was headed toward her kennel at Mile 72.5 of Parks Highway. Helwig packed food for her five dogs, some expensive sled-dog harnesses, her good parka, a few furs, a small suitcase of clothes and a few other random things—such as her bluebird-of-happiness figurine. Later, she’d kick herself for not grabbing more—especially her dog sled. Willow is best known as the home of the Iditarod Trail Sled Dog Race restart, and nearly as many sled dogs as people—about 2,000—live in this unincorporated community, which dots the Parks Highway between Mile 60 and Mile 80. The wildfire started about 1:15 p.m., June 14, 2015, off Sockeye Avenue near Mile 77.5 of the Parks Highway. A few hours later, flames had spread south five miles and began…