Cities and towns, through their home rule powers, hold the key to protecting the long-term quality of their drinking water supplies.  The federal Safe Drinking Water Act establishes the maximum levels of contaminants allowed in public water supplies to meet public health needs, but achieving those quality standards is largely a local responsibility.

Most threats to drinking water quality are related to inappropriate land uses sited in sensitive areas that may impact water sources.  These include aquifer areas that recharge groundwater sources and watershed areas that contribute flow to reservoirs and other surface water sources.  Incompatible land uses sited in these areas may provide a potential pathway for pollutants to flow into source waters.  Since the regulation of land use is largely under the control of local zoning codes, communities have it within their power to implement local protection measures to ensure the quality of their dinking water.  

Over the last 20 years many communities have adopted zoning measures such as Aquifer and Watershed Protection Overlay Districts to restrict land uses that pose a threat to water quality.  MAPC worked with DEP and the MWRA to develop a model aquifer protection zoning overlay bylaw/ordinance and a majority of cities and towns in the region have adopted zoning overlay districts.   However, a few communities have not yet adopted such zoning measures.  In addition, many of the zoning overlay districts on the books were adopted as long as 20 years ago, suggesting that some of them may need to be updated.  Updates to these zoning codes may include two kinds of amendments:

• amending the geographic boundaries of an overlay district to reflect changes in water sources or recharge area delineations
• amending performance standards and/or criteria for land uses that are allowed by right, allowed by special permit, or prohibited

36.a    Municipalities should conduct reviews of land use controls and adopt or update overlay protection districts where necessary

36.b    MAPC should provide models and technical assistance for new or updated water resources protection zoning measures.

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