An earthen dam in Ridgefield that protects Mamanasco Lake must be raised 3 inches if it is to meet new 100 year Connecticut flood standards. Mamanasco Lake is on Mamanasco Road, across the street from Ridgefield High School. The dam was originally created way back in the 1700’s. It has both a dam and spillway, and at one time, it served as the town’s grist mill.