HomeMy WebLinkAboutWater Quality Report 2006 (PDF)
The Aaron River Dam on May 16, the day after the floods of 2006.
2006 Water Quality Report
Cohasset Water Department, 339 King Street, Cohasset, MA 02025 (781) 383-0057 www.cohassetwater.org July 1, 2006
The Cohasset Water Department (DEP ID#
3065000), under the direction of the elected Board
of Water Commissioners, provides public drinking
water to about 2,400 connections 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.
This Water Quality Report describes the sources
of our drinking water and the quality of that water
for the period from January 1 – Dec. 31, 2005.
In 2005 we exceeded the standard for Total
Trihalomethanes (TTHMs) in the first Quarter of the
Year and met the standard for the Second, Third and
Fourth Quarters. We met or exceeded standards for
other contaminants in drinking water.
Where the Water Comes From
The Cohasset Water Department drinking water
comes from two surface water supplies, Lily Pond
(DEP ID# 065-01S), 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 136 acre Aaron River
Reservoir, which can hold a maximum of 550
million gallons of water, is used to supplement Lily
Pond in times of high water demand.
The watershed for Lily Pond and the Reservoir
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 5.2 million
gallons per day (gpd). Our average daily demand is
about 800,000 gallons per day, and the maximum
daily demand, in the summer, is 2.2 million gpd.
Projections show that our existing water supply will
be capable of meeting projected water system
demands for the next 20 years or more.
The Water Department has two well fields - the
Ellms Meadow Well field (ID# 065-02G), which has
been approved for up to 170,000 gallons per day.
The well field will be reactivated in 2006 after the
pump house is rebuilt. The Sohier Street Wells (ID#
065-01G & 03G) are currently out of service.
2005 Water System Improvements
• Replaced 7,150 feet (1.4 miles) of undersized
water mains to improve fire protection and
water quality.
• Replaced 2 fire hydrants, installed 20 new fire
hydrants.
• Numerous improvements to the Lily Pond
Water Treatment Plant process and
instrumentation which resulted in measurable
improvements in drinking water quality
• Acquired over 23 acres of watershed land to
protect drinking water quality.
• Installed the first 5 of 55 raingardens in the
Lily Pond Watershed to reduce nutrient
loading and improve water quality
page 2
2005 Cohasset Water Quality Results
Regulated Contaminants
Date(s) Collected Highest
Detect
Range
Detected
Highest
Average
MCL
or
MRDL
MCLG
or
MRDL
G
Viola-
tion ?
(Y/N)
Possible Source(s) of
Contamination
Inorganic Contaminants
Fluoride (ppm) Daily, 2005 1.47 0.56-1.47 ---- 4 4 No Additive to water to promote strong teeth
Nitrate (ppm) 6/23/05 0.02 ---- ---- 10 10 No
Runoff from fertilizer use; Leaching from
septic tanks, sewage; Erosion of natural
deposits.
Chlorine (ppm) Daily, 2005 1.67 .40-1.67 ---- 4 4 No Water additive used to protect public
health by controlling microbes
Barium (ppm) 6/23/05 0.013 ---- ---- 2 2 No
Discharge of drilling wastes; discharge
from metal refineries; erosion of natural
deposits.
Volatile Organic Contaminants
Total Trihalomethanes
(TTHMs) (ppb) Quarterly, 2005 91 42 - 91 79.6 80 ----- Yes Byproduct of drinking water chlorination
Haloacetic Acids
(HAA5’s) (ppb) Quarterly, 2005 79 ND - 79 28 60 ----- No Byproduct of drinking water chlorination
Radioactive Contaminants
Gross Alpha (pCi/l) 2/17/04 -1.3+/-1.0 ---- ---- 15 0 No Erosion of natural deposits
Gross Beta (pCi/L) 2/17/04 2.9+/-2.2 ---- ---- 50 0 No Decay of natural and man-made deposits
Radium 226 2/17/04 0.3+/-0.2 ---- ---- 0.1 0 No Erosion of natural deposits
Radium 228 2/17/04 1.0+/-0.8 ---- ---- 0.5 0 No Erosion of natural deposits
Synthetic Organic Contaminants
Hexachlorocyclo-
pentadiene (ppb) 6/3/03 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
AL
Viola
tion? Possible Sources of Contamination
Lead (ppb) 9/15/04 9 15 0 2 of 20 No Corrosion of household plumbing systems.
Copper (ppm) 9/15/04
0.80 1.3 1.3
0 of 20 No
Corrosion of household plumbing
systems; leaching from wood
preservatives.
Turbidity TT
Lowest
Monthly %
of Samples
Highest Detected Daily
Value
Violation? Possible Sources of Contamination
Daily Compliance (NTU) 0.3 ---- 0.25 No Soil Runoff
Monthly Compliance At least 95% 96% ---- No
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 (1)
Inorganic
Contaminants
Date(s)
Collected
Results
Average
Detected SMCL ORSG Violation? Possible Sources of Contamination
Sodium (ppm) 6/23/05 32 ---- ---- 20 No Runoff from use of salt on roadways to protect public
safety.
Sulfate (ppm) 6/23/05 5.9 ---- 250 ---- No Natural sources
(1) 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.
page 3
Total Trihalomethanes Violation
The Water System was in violation for the
Total Trihalomethane MCL for the first quarter of
2005. The Water Commission has taken action to
come into compliance with the TTHM regulation,
and did so as of the second quarter of 2005, by
making the following improvements:
• changing to a more effective coagulant
• replacing the filter media
• moving the chlorination point in the plant and
installing baffles in the clearwell
Health Effects Information
Total Trihalomethanes (TTHMs). 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.
Definitions
• 90th Percentile. 9/10 were at or below this level.
• pCi/L. Picocuries per liter (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): Highest level of
contaminant allowed in drinking water. MCLs are set as
close to the MCLGs 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.
Disinfection is necessary to control microbiological
contamination.
• MRDLG (Maximum Residual Disinfectant Level Goal).
Level of a drinking water disinfectant which there is no
known or expected risk to health; do not reflect the
benefits of the use of disinfectants to control
microbiological contaminants.
• NTU (Nephelometric Turbidity Units) Measure of how
clear the water is.
• ORSG. Mass Office of Research and Standards
Guideline Concentration of a chemical in drinking
water, at or below which, adverse health effects are
unlikely to occur after chronic (lifetime) exposure.
• SMCL. Secondary Maximum Contaminant Level These
standards 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/equal to 0.50 NTU
• Variances & Exemptions – State or EPA permission
not to meet an MCL or a treatment technique under
certain conditions.
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.
page 4
Water Commissioners break ground for the new Ellms
Meadow pump station.
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).
Educational Statement Concerning 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.
SWAP Report on Cohasset
The Department of Environmental Protection
(DEP) has prepared a Source Water Assessment
Program (SWAP) Report for the water supply sources
serving the Cohasset Water Department.
The SWAP Report notes that the key issues for
water supply protection are: protection of the Zone A,
protecting the watershed outside Cohasset, public
education, and control of residential uses that might
contaminate the watershed.
The report commends the water system for
mapping storm drains, conducting a study on the
health of Lily Pond, and taking preliminary steps to
develop a lawn care program.
The Water Commission plans to address the
protection recommendations by implementing all the
SWAP recommendations and by implementing our
Surface Water Supply Protection Plan that was
completed and approved by DEP in 2002.
The complete SWAP report is available at the
Water Department. For more information, call the
Water Dept. at 781-383-0057.
Community Involvement
• We encourage public interest and participation in
Cohasset’s decisions affecting drinking water.
• The Water Commission usually meets every other
week at 7:30 pm at the Lily Pond Water
Treatment Plant, 339 King Street.
• Meeting notices are posted at Town Hall. Feel
free to attend and to participate in our meetings.
• Please call Superintendent Eileen Commane at the
Water Department at 383-0057 (fax 383-2906)
with any questions or concerns.
• This report is available at the Water Department,
Town Hall, and the Paul Pratt Memorial Library,
and on our website, www.cohassetwater.org.
Cohasset Board of Water Commissioners
Glenn A. Pratt, Chairman
John McNabb, Vice-Chairman
Nathaniel Palmer, Clerk