Zone I

The protective radius required around a public water supply well or wellfield, as defined in Massachusetts Drinking Water Regulations, 310 CMR 22.02: Definitions. For public water supply system wells with approved yields of 100,000 gpd or greater, the protective radius is 400 feet. Tubular well fields require a 250-foot protective radius. Protective radii for all other public water system wells are determined by the following equation: Zone I radius in feet = [150 x log of pumping rate in gpd] – 350.