Willett Pond is man-made, having been built in 1913 as an industrial water supply for a downstream tannery in Norwood. The pond was built in a natural depression left by a huge lingering ice mass from the last glacial period and is impounded along the east side by a 900 ft. long, 25 ft. high dam and along the southeast side by a 1900 ft. long, 14 ft. high dike. Both structures are structurally sound earthen embankments containing concrete core walls. Pond water level is controlled by a concrete culvert spillway with wooden flashboards which passes through the dam beneath the Bullard St. bridge. The spillway can easily pass the flow ensuing from a 500-year flood or more and additional water can be removed from the pond’s low point via two 20 in. diameter pipelines.