The Chestnut Hill Reservoir in Brighton, at the 22-mile mark of the Boston Marathon course, was the site of a dramatic rescue on September 24. Katie Kellner, 28, who is a member of the BAA racing team, was three miles into what was supposed to be an easy 60-minute run, which included a loop around the 1.5-mile reservoir. She witnessed a dog swimming in the water and a man on the shore calling to the dog. He was a dog walker, who handed off two other dogs to a bystander, then went into the water to pursue the loose dog,...