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Lily Pond
2003 Water Quality Report
Cohasset Water Department, 339 King Street, Cohasset, MA 02025 ID# 3065000 (781) 383-0057 March 29, 2003
The Cohasset Water Department, under the
direction of the elected Board of Water
Commissioners, provides public drinking water for
about 7,100 Cohasset residents and provides and
maintains a water system for fire fighting. We
provide drinking water for almost 90% of the
population of Cohasset, excluding North Cohasset
which get its water from the Aquarion Water
Company of Massachusetts, formerly the Hingham
Mass-American Water Company.
This Annual Water Quality Report describes
water sources and water quality for 2002. We are
pleased to report that your drinking water meets or
exceeds all applicable drinking water standards.
Where Your Water Comes From
Your drinking water comes from two surface
water supplies, Lily Pond (DEP ID# 065-01S),
pictured above, and the Aaron River Reservoir (DEP
ID# 065-02S). Lily Pond has a maximum capacity of
about 100 million gallons of water and is 52 acres in
size. The Reservoir, which can hold a maximum of
323 million gallons of water, is used to supplement
Lily Pond in times of high water demand.
The watershed for Lily Pond and the Reservoir
(see enclosed map) covers an area of 5,892 acres,
9.21 square miles. Only 2,339 acres (or 40%) is in
Cohasset. The safe yield of our surface water supplies
is 3.5 million gallons per day (gpd). Our average
daily demand is about 710,000 gallons per day, and
the maximum daily demand, during the summer, is
currently about 2.2 million gpd. Projections show that
our existing water supply will be capable of meeting
water system demand for the next 20 years or more.
Our two wellfields, the Sohier Street Wells (ID#
065-01G & 03G) and the Ellms Meadow Wellfield
(ID# 065-02G), are currently out of service but are
planned to be reactivated. The Water Commission
has replaced the wells at the Ellms Meadow
Wellfield, which has been approved for up to
170,000 gallons per day, and is currently preparing to
build a new pumphouse to reactivate the wellfield.
We are currently looking for a new site for the Sohier
Street Wells, with mitigation funds from the MBTA,
because the existing well is located too close to the
right of way of the Greenbush Restoration Project.
2002 Water System Improvements
In 2002, to improve water quality and fire protection,
the Water Commission:
Replaced 4,580 feet, or about 9/10th of a mile of
undersized water mains.
Replaced 18 fire hydrants, installed 9 new hydrants,
fixed 3 leaks, repaired 46 meters, installed 29 new
meters, and flushed the entire distribution system.
Started to implement the Surface Water Supply
Protection Plan to protect drinking water quality
Started major improvements to the Lily Pond Water
Treatment Plant, including installation of Variable
Frequency Drives for the finished water pumps.
page 2
2002 Cohasset Water Quality Results
The Cohasset Water Department tests for over 80 contaminants on a regular basis, in accordance with State and
Federal requirements. The following contaminants were the only ones detected in the most recent testing required
under the regulations. There were no violations of any applicable drinking water quality regulation.
Regulated
Contaminants Date(s) Collected Highest
Detect
Range
Detected
Highest
Average
MCL
or
MRDL
MCLG or
MRDLG
Violat
ion
(Y/N)
Possible Source(s) of
Contamination
Inorganic Contaminants
Fluoride (ppm) Daily, 2002 1.25
1.00 -
1.25 1.12 4 4 No
Erosion of natural deposits; water additive
which promotes strong teeth; discharge
from fertilizer and aluminum factories
Volatile Organic Contaminants
Chlorine (ppm) Daily, 2002 1.45
1.17 -
1.45
1.35 44NoWater additive used to control microbes
Total Trihalomethanes
(TTHMs) (ppb) (1)
2/20/02, 5/21/02,
09/25/02, 12/18/02 82.7 60.4 –
82.7 68.7 80 ----- No(1) Byproduct of drinking water chlorination
Haloacetic Acids
(HAC’s) (ppb) (1)
2/27/02, 5/21/02,
9/25/02, 12/18/02 60.6 35.4 –
60.6 61.9 60 ----- No(1) Byproduct of drinking water disinfection
Radioactive Contaminants
Gross Alpha (pCi/l)
(minus uranium)3/21/00 1.7 ---- ---- 15 0 No Erosion of natural deposits
Gross Beta/photon
emitters (pCi/L)3/21/00 1.3 ---- ---- 50 0 No Decay of natural and man-made deposits
Synthetic Organic Contaminants
Hexachlorocyclo-
pentadiene (ppb)6/21/00 0.1 ---- ---- 50 50 No Discharge from chemical factories
Lead & Copper (2)
(20 sites sampled each)Date(s) Collected 90th
Percentile
Action
Level MCLG # sites above
Action level
Viola
tion?Possible Sources of Contamination
Lead (ppb) 8/22/01
12 15 0
2 of 20 No Corrosion of household plumbing
systems; Erosion of natural deposits
Copper (ppm) 8/22/01
0.318 1.3 1.3
0 of 20 No
Corrosion of household plumbing
systems; Erosion of natural deposits;
Leaching from wood preservatives
Turbidity TT
Lowest
Monthly %
of Samples
Highest Detected Daily
Value Violation?Possible Sources of Contamination
Daily Compliance (NTU) 5 ---- 0.07 No
Monthly Compliance At least 95% 100% ---- No
Soil Runoff
Turbidity is a measure of the cloudiness of the water. We monitor it because it is a good indicator of water quality.
*Monthly turbidity compliance is related to a specific treatment technique (TT). Our system filters the water so at least 95% of our samples each month
must be below the turbidity limits specified in the regulations.
Unregulated Contaminants
Inorganic
Contaminants
Date(s)
Collected Result
Average
Detected SMCL ORSG Possible Sources of Contamination
Sodium (ppm) 5/21/02 21.2 n/a ---- 20
Natural sources; runoff from use as salt on roadways; by-
product of treatment process
Sulfate (ppm)5/21/02 29.9 n/a 250 ----
Natural sources
Volatile Organic
Compounds
Date(s)
Collected
Highest
Detect
Range
Detecte
d
Highest
Averag
e
MCL
or
MRD
MCLG
or
MRDLG
Viola
tion
(Y/N)
Possible Source(s) of
Contamination
Hexachlorobutadiene
(ppb)3/08/02 0.6 ---- ---- n/a n/a No
Used to make rubber compounds; used as
a solvent, and to make lubricants; used as
a heat transfer liquid and hydraulic fluid.
(1) Cohasset is not required to test for TTHM’s or HAC’s, because systems serving less than 10,000 are not required to until after December,
2003. However, we are voluntarily testing for TTHM’s & HAC’s and are taking measures to reduce their levels in drinking water by
continuing to rehabilitate water mains, annually flushing the distribution system, and by changing plant operations where needed to reduce
TTHM & HAC levels. These levels have been going down -- in the last quarter of 2002, TTHM was 60.4 and HAC was 35.4.
(2) We received a monitoring waiver in 1998 for Lead & Copper and were required to test for them only every three years.
(3) Unregulated contaminants are those for which EPA has not established drinking water standards. The purpose of unregulated
contaminant monitoring is to assist EPA in determining their occurrence in drinking water and whether further regulation is warranted.
Exceeding a SMCL or ORSG for an unregulated contaminant is not a violation. We are taking action to reduce sodium levels.
page 3
Educational Statement on Lead
Infants and young children are typically more
vulnerable to lead in drinking water than the
general population. It is possible that lead levels at
your home may be higher than at other homes in
the community as a result of materials used in
your home’s plumbing. If you are concerned about
elevated lead levels in your home’s water, you
may wish to have your water tested. Flush your
tap for 30 seconds to 2 minutes before using tap
water to reduce lead content. Additional
information is available from the Safe Drinking
Water Hotline, 1-800-426-4791.
Aaron River Reservoir
Health Effects of Some
Detected Contaminants
Although there were no exceedances of any applicable
water quality regulation, following are the health
effects for the contaminants that were detected in
relatively high concentrations.
Total Trihalomethanes (TTHM’s). Some people
who drink water containing trihalomethanes in excess
of the MCL over many years experience problems with
their liver, kidneys, or central nervous system. They
may have an increased risk of getting cancer.
Haloacetic Acids. Some people who drink water
containing HAC’s in excess of the MCL over many
years may have an increased risk of getting cancer.
Sodium. There is no state or federal MCL for sodium.
Monitoring is required to provide information to
consumers and health officials that are concerned about
sodium intake due to dietary precautions. If the level if
over 20 ppm, and you are on a sodium-restricted diet,
you should consult a physician about this level of
sodium in the water.
Definitions
• 90th Percentile. Out of every 10 homes, 9 were at
or below this level.
• pCi/L. Picocuries per liter (measure of
radioactivity).
• ppb - parts per billion, micrograms per liter (ug/l)
• ppm - parts per million, milligrams per liter (mg/l)
• AL (Action Level). The concentration of a
contaminant that, if exceeded, triggers treatment or
other requirements which must be followed.
• MCL (Maximum Contaminant Level): The highest
level of a contaminant that is allowed in drinking
water. MCL's are set as close to the MCLG's as
feasible using the best available treatment
technology.
• MCLG (Maximum Contaminant Level Goal): The
level of a contaminant in drinking water below
which there is no known or expected risk to health.
MCLGs allow for margin of safety.
• MRDL (Maximum Residual Disinfectant Level).
The highest level of a disinfectant allowed in
drinking water. There is convincing evidence that
addition of a disinfectant is necessary for control of
microbiological contamination.
• MRDLG (Maximum Residual Disinfectant Level
Goal). The level of a drinking water disinfectant
which there is no known or expected risk to health.
MCLG’s do not reflect the benefits of the use of
disinfectants to control microbiological
contaminants.
• NTU - Nephelometric Turbidity Units; a measure
of how clear the water is.
• ORSG. Massachusetts Office of Research and
Standards Guideline – This is the concentration
of a chemical in drinking water, at or below which,
adverse health effects are unlikely to occur after
chronic (lifetime) exposure. If exceeded, it serves
as an indicator of the potential need for further
action.
• SMCL. Secondary Maximum Contaminant Level
– These standards are developed to protect the
aesthetic qualities of drinking water and are not
health based.
• TT (Treatment Technique) - 95% of all monthly
samples taken must be less than or equal to 0.50
NTU
• Variances & Exemptions – State or EPA
permission not to meet an MCL or a treatment
technique under certain conditions.
page 4
Contaminants in Drinking Water
Drinking water, including bottled water, may
reasonably be expected to contain at least small
amounts of some contaminants. The presence of
contaminants does not necessarily indicate that water
poses a health risk. More information about
contaminants and potential health effects can be
obtained by calling the EPA’s Safe Drinking Water
Hotline (1-800-426-4791).
The sources of drinking water (both tap water
and bottled water) include rivers, lakes, streams,
ponds, reservoirs, springs, and wells. As water
travels over the surface of the land or through the
ground, it dissolves naturally-occurring minerals
and, in some cases, radioactive material, and can
pick up substances resulting from the presence of
animals or from human activity.
Contaminants that may be present in source
water include:
• Microbial contaminants, such as viruses and
bacteria, which may come from sewage
treatment plants, septic systems, agricultural
livestock operations, and wildlife.
• Inorganic contaminants, such as salts and metals,
which can be naturally-occurring or result from
urban stormwater runoff, industrial or domestic
wastewater discharges, oil and gas production,
mining, or farming.
• Pesticides and herbicides, which may come from
a variety of sources such as agriculture, urban
stormwater runoff, and residential uses.
• Organic chemical contaminants, including
synthetic and volatile organic chemicals, which
are byproducts of industrial processes and
petroleum production, and can also come from
gas stations, urban stormwater runoff, and septic
systems.
• Radioactive contaminants, which can be
naturally-occurring or be the result of oil and gas
production and mining activities.
To ensure that tap water is safe to drink, the DEP
and EPA prescribe regulations which limit the
amount of certain contaminants in water provided by
public water systems. The Food and Drug
Administration (FDA) and the Mass. Department of
Public Health (DPH) regulations establish limits for
contaminants in bottled water which must provide
the same protection for public health.
Vulnerable Populations Warning
Some people may be more vulnerable to
contaminants in drinking water than the general
population. Immuno-compromised persons such as
persons with cancer undergoing chemotherapy,
persons who have undergone organ transplants,
people with HIV/AIDS or other immune system
disorders, some elderly, and infants can be
particularly at risk from infections. These people
should seek advice about drinking water from their
health care providers. EPA/CDC guidelines on
appropriate means to lessen the risk of infection by
Cryptosporidium and other microbial contaminants
are available from the Safe Drinking Water Hotline
(1-800-426-4791).
The Aaron River Reservoir, which first came into
service May 11, 1978. Please come to our 25th
Anniversary Event, May 11, 2003, at the Reservoir
Community Involvement
• We encourage public interest and participation in
our Town’s decisions affecting drinking water.
• The Water Commission usually meets every
other week at 8:00 pm at the Lily Pond Water
Treatment Plant, 339 King Street. Meeting
notices are posted at Town Hall. Please feel free
to attend and to participate in our meetings.
• Please call the Water Department at 383-0057
(fax 383-2906) or call any of the Water
Commissioners, with any questions or concerns.
• Chairman John McNabb can be reached at 383-
6202 or at mcnabbj@mindspring.com.
• This report is available at the Water Dept., Town
Hall, and the Paul Pratt Memorial Library.
Cohasset Board of Water Commissioners
John K. McNabb, Jr., Chairman
Robert E. Kasameyer, Vice-Chairman
Glenn A. Pratt, Clerk