REVEICED BY MAIL
3:50 PM, Apr 21, 2015
IMPORTANT INFORMATION ABOUT YOUR DRINKING WATER
Este informe contiene informaci6n importante sobre Su agua potable.
Para una copia de este articulo en espanol, por favor llame al 707-942-2828'
City of Calistoga Has Detected Level of Disinfection
Byproducts Above Drinking Water Standards
Our water system recently exceeded a new drinking water standard for disinfection byproducts called
total trihalomethanes (TTHM) in the vicinity of your service meter. Although this is not an emergency,
as our customers, you have a right to know what you should do, what happened, and what we are
doing to correct this situation.
What should I do?
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No specific corrective actions are needed. You do not need to boil your water or use an
alternative water supply (e.9., bottled water).
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This is not an immediate risk. lf it had been, you would have been notified immediately. Some
people who drink water containing disinfection byproducts in excess of the maximum limit over
many years may experience liver, kidney, or central nervous system problems, and may have
an increased risk of getting cancer. These diseases, however, are not caused solely by
chemicals in drinking water, but result from many other factors.
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lf you have specific health concerns regarding the consumption of this water, you may wish to
consult your health care provider.
What happened to create the TTHM's level above the regulation level?
To protect drinking water from disease-causing organisms, or pathogens, chlorine is added to
drint<ing water as L disinfectant. However, disinfection byproducts can form when organic-rich
water, is disinfected. A major challenge for the City of Calistoga and all municipal water
systems is how to control and limit risks from pathogens and simu.ltaneously minimize
disinfection byproduct formation. Disinfection byproducts tend to be highest when naturallyoccurring organic matter is elevated in our surface water supplies from the Delta due to
protongdd diought conditions, winter rains, and during periods of long detention times in the
North Bay Aqueduct water transmission main.
We routinely monitor for the presence of drinking water contaminants throughout our. entire
water system. As of October 2012, the standard that applies to the City of Calistoga's system
for disinfection byproducts changed significantly. The maximum limit for the annual average of
TTHM',s at each sampling location is 80 micrograms per liter (ug/L).
At the City's sample location at 414 Washington Street the TTHM results received on February
4,2015 were 10i ug/l and averaged 85 ul/L over the last twelve months at this sampling
location. This is above the maximum level of 80 ug/L and therefore requires the City to inform
our customers of the results and the reason why their water did not meet regulations.
Due to the drought in 2014 the City of Calistoga made the conscious decision to "bank" our
local surface waler supply at Lake Kimball and use more Delta water from the State Water
Project delivered througfr the North Bay Aqueduct (NBA) transmission main and which is
treated by the City of Napa. This decision was made to preserve the local water supply in the
event the State curtailed our NBA supply in 2014. lf the State had curtailed our water from the
Delta, and we had not managed our local supply well, we could have been severely limited in
our ability to meet the City's water demands.
How we manage our water supply sources plays a significant role in the formation of TTHM
levels. When we receive water from the Delta, the water travels up to 38 miles in a pipeline
before it enters our water distribution system. Detention time in the NBA transmission main, or
the time it takes for the water to travel in that pipeline, is a major variable to formation of
TTHM's. Another contributing factor is the prolonged drought, the accumulation of organic
material in the watershed, and the unusual low flows in the Delta due to the drought.
What is being done?
The City is operating our KimballWater Treatment Plant more often and it has been providing
water at a lower TTHM value than the water we receive through the NBA transmission line.
We will continue to operate the KimballWater Plant to the greatest extent possible, while at
the same time taking into consideration current water supply projections to ensure an
adequate local supply during peak demand times.
We are managing our water tanks to circulate more water through the tank on a more frequent
interval. More circulation leads to lower TTHM values. We also recently installed a mixing
device in the Mt. Washington tank which should help reduce TTHM formation. We are also
exploring methods to improving mixing in the Feige storage tank.
We continue to test water samples and evaluate TTHM results both from Kimball supplied
water and water from the NBA. Future actions and plans are dependent on the results of
these tests. We will be working closely with the City of Napa to develop appropriate methods
to reduce formation of TTHM's. At the present time we do not have sqfficient information to
make recommendations for capital investments or when those may occur and we will be
working closely with the State Division of Drinking Water to develop appropriate corrective
action.
For more information, please contact Michael Kirn at (707) 942-2828 or 414 Washington Street,
t
Calistoga, CA
94515.
Please share this information with all the other people who drink this water, especially those who may
not have received this notice directly (for example, people in apartments, nursing homes, schools, and
busrnesses,). You can do this by posting the public notice in a public place or distributing copies by
hand or mail.
Secondary Notification Requirements
Upon receipt of notification from a person operating a public water system, the following notification
must be given within 10 days [Health and Safety Code Section 1 16450(9)]:
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o
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SCHOOLS: Must notify school employees, students, and parents (if the students are minors).
RESIDENTIAL RENTAL PROPERTY OWNERS OR MANAGERS (including nursing homes
and care facilities): Must notify tenants.
BUSINESS PROPERTY OWNERS, MANAGERS OR OPERATORS: Must notify employees
of businesses located on the property.
This notice is being sent to you by the City of Calistoga.
State Water System lD#: 2810002. Date distributed: April 10, 2015