The festival at 66 State St. takes off at 9 a.m. with a 5K run through the completed Lake Wallace Sensory Trail. What is Lake Wallace? Tucked behind the Police Department and Recreation Department, Lake Wallace and Foley Field were once part of the Belchertown State School campus. Lake Wallace has been a living laboratory for students to learn biodiversity surveys and scientific observation. “It was thrown out there that we should just throw a Lake Wallace Fall Fest, then we realized it was a good idea.”The festival serves not only as a celebration, but also as a fundraiser for the new Lake Wallace gift account.