The report “Assessment of Arsenic Concentrations in Domestic Well Water, by Town, in Maine, 2005–09” and maps now are posted online.
harmful arsenic levels have been found in private water wells in towns across Maine where elevated
arsenic risks were not previously suspected. Arsenic levels in some private
wells exceeded the federal safety standard for public drinking water by 10 to 100
times or more, according to findings recently released by the U.S. Geological
Survey (USGS). The study is the largest of its kind in Maine.
large differences in concentrations from well to well, even at the town level,
so residents need to test their wells to know their arsenic level,” says USGS
scientist Martha Nielsen, who led the study in cooperation with the Maine Center
for Disease Control and Prevention (CDC). “We are working with the Maine CDC to
identify towns throughout the state where elevated arsenic levels are common
but have gone mostly unnoticed.”
USGS has been working nationwide for many years to test ground water for
arsenic,” says Robert Lent, Director of the USGS
“Arsenic levels in this study are some of the highest we have seen in private
wells,” explains Lent. “Nearly half of Maine’s
population use private wells for drinking water, so this issue quite literally
hits home for many people.”
takes one person in a town to be an advocate and champion to encourage fellow
citizens to have their wells tested. The variability in arsenic concentrations,
even at the town level, shows that testing is crucial for homeowners in
assessing personal risk,” notes Lent.
CDC is distributing posters and brochures to selected town offices based on the
proportion of residents on private wells and information about the presence of
wells with arsenic. The Maine CDC has worked in partnership with towns
to prevent the spread of diseases.
mapping effort is helping us to better target our efforts to promote testing of
private wells for arsenic,” says state toxicologist Andrew Smith with the Maine
CDC. “Statewide only about 40 percent of private water well owners have tested
for arsenic, so it is crucial that we target our resources to the highest risk
areas and nearby areas where we lack data,” Smith reveals.
study, scientists examined data from more than 11,000 wells in 530 cities,
towns and townships in Maine.
Data came from water samples submitted to the Maine Health and Environmental
Testing Laboratory between 2005 and 2009.
levels ranged from less than the detection limit of 0.5 micrograms/liter (ug/L)
to 3,100 ug/L. The federal safety standard for public drinking water is 10
results were summarized at the town level to produce maps showing arsenic
concentrations by town where sufficient samples were collected. The maps
provide a much greater spatial resolution of arsenic in private wells across
the state than have previous efforts.
confirmed many areas already known to have high levels of arsenic in ground water
and revealed for the first time, towns that should be further investigated,” says
Nielsen. “Several towns in eastern Washington and central Penobscot counties,
and in the southern parts of Piscataquis and Somerset counties have elevated arsenic that
is more widespread than we realized.”
the study included more than 11,000 wells, this is a relatively small sample of
all the private wells in Maine.
shows the difficulty of predicting arsenic concentrations at the local level,
and should signal to everyone with a private well that the only way to know
about arsenic concentrations in their well is to have their water tested,” states
with more than 20 wells in the database had at least one well with arsenic
levels greater than the safety standard. In a few towns, more than 50 percent
of the sampled wells had arsenic levels greater than the safety standard. In
considering these data, it is important to understand that the wells do not
represent a random sample of the state. These data, however, provide a better
indicator of potential arsenic hotspots than any other dataset.
is probably the biggest factor in the distribution of arsenic in private
wells,” explains Nielsen. “But the degree of local variability means that we
can't simply use bedrock type to determine all the areas in the state where it
is critical that people test their wells.”
water with arsenic above safety standards has been linked to an increased risk
for skin, bladder and lung cancer; to reproductive and developmental problems;
diabetes; and effects on the immune system. Private water wells are not
regulated under the federal Safe Drinking Water Act, and well owners typically
are responsible for testing the quality of their drinking water.
arsenic levels are not limited to Maine.
A recent national USGS study found arsenic concentrations above the federal drinking
water standard in more than 10 percent of private wells in New
England’s bedrock aquifers compared to about 7 percent of private
well owners can contact the Maine Drinking Water Program for guidance and
information about well maintenance, testing, and in-home water treatment
options. Access the USGS Maine Water Science Center
for more information about water in Maine.
Information about water quality nationwide is found on the USGS National
Water-Quality Assessment Program site.
Water Well Tests Show Elevated Arsenic Levels in Maine
December 13, 2010