Carlisle's Development Standards regarding Groundwater
Years ago, the Select Board, the Planning Board and the
Board of Health adopted Development Standards to serve as a general policy statement
for regulating development in Carlisle. You can read more about these standards below.
The Development Standards are part of the Planning Board’s rules and regulations and
start at page 69 in the link attached here: Rules & Regs/supercopy 5/16/02 (ML6230.DOC1)
The Development Standards state the following:
In keeping with over 200 years of development history in Carlisle, new development should be consistent with the immediate neighborhood, make a concerted effort not to detract from existing homes and land development patterns,
and assure that development will not adversely impact the environment,
particularly the private water sources exclusively relied upon by Carlisle residents.
The Town has limited water resources, and has no piped water system—but rather, all homes, businesses, and
municipal users rely on individual on-site water wells—and no public wastewater treatment system.
Two-acre zoning (one acre in the Town Center) is thus important to the Town of Carlisle to protect water availability and quality. Further, Carlisle has a small population of barely over 5,500 people, a limited tax base, no public transit, and lacks
the roadway and utility infrastructure required to support commercial development or other dense development.
As a result, the Planning Board must be sensitive to the burden and impact of any increase in housing density.
Climate Change is going to make all these risks worse!
In late 2022, UMass Boston released a report analyzing the effects of climate change on groundwater in Eastern Massachusetts. The findings are sobering. With respect to Carlisle’s immediate area (approximately 12 inland communities including Acton, Concord, Lincoln and Carlisle), the report states:
Water for drinking, irrigation, and other uses from groundwater sources depends on
adequate aquifer recharge to sustain water withdrawals. Most communities in the
MAGIC subregion (see Figure 2.1) have private drinking water wells or municipal
supplies that include public groundwater sources and some supplementary private
wells. Drinking water infrastructure in this subregion has been assessed as highly
vulnerable to drought and changes in precipitation.
In 2016, nearly 33% of the watershed sub-basins of this subregion were classified as net depleted according to the Sustainable Water Management Initiative (SWMI), meaning that the groundwater
withdrawal rates exceed groundwater recharge (MAPC, 2017). A warming climate can
exacerbate this condition through reductions in aquifer recharge and declining
groundwater levels, either through increasing rates of AET and/or decreasing rates of
infiltration, especially in the long term.
The decrease in annual recharge rates predicted by the PRMS model suggests that aquifers in these communities may be adversely affected by a warming climate after 2030. This projected reduction in natural recharge—coupled with population and water-demand increases, more impervious
area, and higher temperatures—may result in less water available for drinking and other
uses if mitigating policies (water conservation and recharge or infiltration basins) are not
implemented.
Here is a link to the UMass Report:
umb-rpt-groundwater-10.22-16-phk-11-1-22-final.pdf
