Land Use Offers Clues to Water Quality

Much of the work of the Cape Cod Commission, the Massachusetts Department of Environmental Protection, local governments, and individual water suppliers has focused on protecting water quality in public water supplies and on determining potential locations for new wells. To identify potential threats to the water supply, these organizations have mapped the zones of contribution (ZOCs) for the supply wells so that land use in those zones can be restricted, if necessary, to protect water quality in the wells. The ZOC is the land area above the aquifer that contributes water to a well under the most severe pumping and recharge conditions that can be realistically anticipated. Silent Spring Institute researchers look closely at ZOCs for possible sources of contamination by chemicals that may be linked to breast cancer. Because of this potential for contamination, public water supplies are regularly monitored to ensure that they meet existing health standards.

Maps for the towns of Eastham and Wellfleet are not included because there is no public water distribution system for these two towns. All residents of these towns have private drinking water wells. ZOCs are shown for all wells for which they were required to be delineated by state regulation.