| WHERE
YOUR WATER COMES FROM
The Daly City water system is supplied equally from
two sources: the San Francisco Water Department and
our own local wells. San Francisco is supplied primarily
by their surface water system which is mostly reliant
on the Hetch Hetchy Watershed and, to a lesser degree,
local reservoirs.
Hetch Hetchy Watershed
The Hetch Hetchy Watershed, a 459-square mile area
located in Yosemite National Park at the headwaters
of the Tuolumne River, provides approximately 80 percent
of the San Francisco Water System (SFPUC) supply.
The Hetch Hetchy system captures water inflows from
the watershed in the Hetch Hetchy Reservoir. This
reservoir, the primary source, is filled by spring
snowmelt, runoff and the Tuolumne River. The water
in the Hetch Hetchy Reservoir is treated but not filtered
because it is of such high quality. The water collected
from Cherry and Eleanor Reservoirs in the Hetch Hetchy
System are a backup supply source used primarily during
drought situations and was not used during 1999.
Alameda and Peninsula Watersheds
The Alameda and Peninsula watersheds provide the remaining
20 percent of the SFPUC water system. The Alameda
watershed, located in the East Bay, represents about
10 percent of the total water supply, with water captured
and stored in two reservoirs; Calaveras and San Antonio.
The Peninsula watershed, representing the remaining
10 percent of the SFPUC supply, captures runoff in
three reservoirs: Crystal Springs, San Andreas and
Pilarcitos.
The five reservoirs in the Alameda and Peninsula watersheds
capture rain, local runoff and some also store Hetch
Hetchy water for use by the SFPUC. The water from
Hetch Hetchy Reservoir that is stored locally is treated
and filtered as is any local water source. Also SFPUC's
water has been fluoridated for nearly 50 years.
During 2000, the SFPUC will conduct a Drinking Water
Assessment and Protection Program audit as required
by the 1996 amendments to the Safe Drinking Water
Act. The audit will be similar to sanitary surveys
previously conducted annually, including 1999, in
the Hetch Hetchy Watershed.
Daly City's Wells (Groundwater)
The SFPUC supply comes from surface water reservoirs.
The term "Surface Water" refers to water that is collected
at ground level. Wells comprise what is termed "groundwater"
or water that is stored below the earth's surface.
Half of the water served by the Daly City Water System
is from our local wells. There were six wells in active
service during 1999. Groundwater is, in many ways,
a much more protected source than surface water. We
draw water from an average depth of 300 feet below
ground from a massive aquifer known as the Westside
Basin that serves a large portion of the Northern
San Mateo Peninsula and extends north to Golden Gate
Park in San Francisco. Because of its protected environment
and the consistency of our monitoring results, our
well water is only required to have a disinfectant
added to it prior to being served in our system. The
disinfectant used is sodium hypochlorite (a concentrated
liquid bleach). This is much safer to store and use
than the pressurized containers of pure chlorine which
were used for many years. The change to hypochlorite
was done over the last three years and is now complete
in the Daly City Water System. This is much safer
for you and the City's staff who operate and maintain
the systems. It should be noted that the City's wells
are checked regularly for bacteriological levels,
and the untreated well water is consistently analyzed
as "non-detect" for total coliform organisms. Daly
City well water is blended with San Francisco water
and then distributed throughout the community. Results
from October 1999 nitrate testing showed detected
amounts of nitrate in excess of the MCL of 45 mg/L
(ppm) at Well #4 (61.1 mg/L) and the A Street Well.
(47.9 mg/L). Nitrate is one of the major anions in
natural water, but concentrations can be greatly elevated
due to leaching of nitrogen from fertilizers. Subsequent
testing at Well #4 and the A Street Well showed a
decreased concentration of nitrate under the MCL.
While there are no significant health effects of nitrate
levels in your tap water due to blending, the following
information statement is required because of the elevated
findings in the wells and is not an indicator or statement
of the water served to you.
Nitrate: Nitrate in drinking
water at levels above 45 mg/L is a health risk for
infants of less than six months of age. High nitrate
levels in drinking water can interfere with the capacity
of an infant's blood to carry oxygen, resulting in
a serious illness; symptoms include shortness of breath
and blueness of the skin. High nitrate levels may
also affect the ability of the blood to carry oxygen
in other individuals, such as pregnant women and those
with certain specific enzyme deficiencies. Nitrate
levels may rise quickly for short periods of time
because of rainfall or agricultural activity. If you
are caring for an infant, you should ask advice from
your health care provider, or choose to use bottled
water for mixing formula and juice for your baby.
If you are pregnant, you should drink bottled water.
How Do Drinking Water Sources
Become Polluted?
The sources of drinking water (both tap and bottled)
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, even radioactive
material. Surface waters in particular can be susceptible
to substances resulting from the presence of animals
or human activity.
Contaminants that may be present in source waters
include:
Microbial Contaminants,
such as viruses and bacteria, which may come from
septic systems, agricultural livestock operations
and wildlife.
Inorganic Contaminants,
such as salts and minerals, which can be naturally
occurring or result from urban stormwater runoff,
industrial or domestic wastewater discharges, oil
and gas production, mining or farming.
Organic Chemical Contaminants,
including synthetic and volatile organics which are
by-products of industrial processes and petroleum
production and can also come from septic systems,
urban stormwater runoff, agricultural chemicals such
as chemical fertilizers, and gas stations.
MTBE, a gasoline additive,
has become a recent water quality concern. This organic
contaminant has rapidly been made a primary contaminant
by DHS and is regularly monitored. All tests for MTBE
in the City's wells and distribution system have been
"Non-Detect".
Radioactive Contaminants,
which can be naturally occurring or the result of
oil and gas production and mining activities
Pesticides and Herbicides
may come from a variety of sources such as agriculture,
urban stormwater runoff and residential uses
How Do We Know Our Water
Is Safe?
In order to insure tap water is safe to drink, the
US EPA and the California Department of Health Services
(DHS) prescribe regulations which place strict limits
on many contaminants that can be present in water
supplied in public water systems. Department regulations
also establish limits for contaminants in bottled
water that provide the same protection for public
health. In addition, each step in the water distribution
process provides an opportunity to introduce preventative
measures, or "barriers", to prevent contaminants from
reaching the consumer. These barriers include source
protection, water treatment and effective operation
and maintenance of the distribution system.
Source Protection is
the primary barrier for water pollution. A contaminant
that does not get into the water source does not need
to be removed. SFPUC maintains a comprehensive watershed
control and management program to protect source water.
The water from Hetch Hetchy Reservoir in Yosemite
National Park is so well protected that the Hetch
Hetchy water supply is one of only six major water
supplies in the country that is exempt from filtration.
SFPUC controls activities on the watershed lands around
their East Bay reservoirs, limiting activities to
those compatible with maximum protection of the water
quality.
High Quality Hetch Hetchy
Water Maintains Filtration Exemption
The Hetch Hetchy Reservoir water supply meets all
Federal and State criteria for watershed protection,
disinfection, treatment, bacteriological quality and
operational standards. As a result the USEPA granted
the Hetch Hetchy water source a filtration exemption
so that water from this source does not require filtration
treatment to insure its safety.
How does the SFPUC maintain the filtration exemption?
They monitor Hetch Hetchy weather conditions, water
turbidity levels, coliform bacteria levels, pathogens
and parasite concentrations. Also, they comply with
disinfection, sampling and reporting requirements,
as well as conduct regular inspections of the protected
Hetch Hetchy watershed and reservoirs.
Daly City, through proper design, construction, operation
and maintenance, achieves the same high level of source
protection at our six active wells. The quality of
the water supplied by our wells is also high enough
to not require further treatment other than disinfection
for your protection. We are committed to providing
the highest quality and safety in the water provided
by our system.
Water Treatment is the
next protective barrier. Water from the remote Hetch
Hetchy reservoir and our wells are unfiltered because
they meet all state and federal requirements without
filtration. Water from the other Bay Area watersheds
near populated areas is filtered to meet standards
for clarity. All of our water is disinfected with
either chlorine or sodium bisulfite (concentrated
bleach) to meet state and federal quality standards.
Effective Operation and Maintenance
of the distribution system assures that the water
maintains its quality as it travels through the system
to your tap. A slight chlorine residual is maintained
in the distribution system to prevent any regrowth
of organisms during storage and transmission of the
water as it travels to you. Active flushing of water
mains and rotation of stored water supplies also keeps
the water fresh and limits growth of organisms. Daly
City conducts continuous water quality monitoring
and testing to assure your drinking water is safe
and healthy.
Daly City, working with the San Mateo County Health
Department, maintains an active cross connection control
program to prevent the intrusion of potentially harmful
materials into the drinking water system. Cross connection
control is done by isolating hazards (irrigation systems,
boilers, cooling towers, fire sprinklers, etc.) from
the drinking water supply by requiring and overseeing
the installation of approved backflow prevention devices.
The devices are annually inspected and certified by
specially trained staff to insure their continued
effectiveness.
However, it is recognized that some people may be
more vulnerable to contaminants in drinking water
than the general population. Immuno-compromised persons,
such as those undergoing chemotherapy, persons who
have undergone organ transplants, people with HIV/AIDS
or other immune system disorders, patients on dialysis
and some elderly residents, infants and pregnant women,
may be particularly sensitive to any substances in
their water. Individuals in these circumstances may
require a specially prepared or treated source for
their water needs that can't be met by a public water
system. These people should seek the direct advice
of their health care provider. Further information
can also be obtained from the EPA/Centers for Disease
Control, Safe Drinking Water Hotline at (800) 426-4791.
Definitions for Understanding
the Water Quality Monitoring Results Summary
The following definitions are important to better
understand the data summary which is presented as
part of this report.
Public Health Goal (PHG):
The level of a contaminant in drinking water for which
there is no known or expected associated health risk.
PHG's are non-enforceable targets set by the California
Environmental Protection Agency (Cal EPA).
Maximum Contaminant Level Goal
(MCLG): The level of a contaminant in drinking
water for which there is no known or expected health
risk. MCLG's are set by the U.S. Environmental Protection
Agency (US EPA).
Maximum Contaminant Level (MCL):
The highest level of a contaminant that is allowed
in drinking water. Primary MCL's are set as close
to the PHG's and MCLG's as is economically and technically
feasible. Secondary MCL's are set to protect odor,
taste and appearance of drinking water.
Primary Drinking Water Standard: MCL's for
contaminants that affect health along with their monitoring
and reporting requirements and water treatment requirements.
Treatment Technique: A required process intended
to reduce the level of a contaminant in drinking water.
Regulatory Action Level: The concentration
of a contaminant which, if exceeded, triggers treatment
or other requirements which a water system must follow.
Other Health Related Information
Cryptosporidium and Giardia
Cryptosporidium and giardia are both parasitic microbes
commonly found in most surface water supplies. Both
can cause diarrhea, stomach cramps, upset stomach
and slight fever. They are tested for monthly by the
SFPUC in both their reservoirs and treated distribution
system.
Very low levels of cryptosporidium are detected about
6% of the time in the source waters. The average level
is less than one cryptosporidium organism per 100
liters of water. This equals about one organism in
25 gallons of water. There were no detected levels
of cryptosporidium in the treated distribution system.
Giardia is a slightly more prevalent organism and
was detected in the source reservoirs about 15% of
the time. The detected levels were again quite low,
one giardia per 100 liters. Slight amounts were occasionally
found in the treated distribution system as well.
The levels again stayed at one giardia per 100 liters
of water, or one organism per about 25 gallons of
water.
It can be reasonably expected to find minute levels
of contaminants, including cryptosporidium and giardia,
in drinking water, including bottled water. The presence
of minute levels of contaminants in water does not
necessarily indicate that the water has the potential
for health risk or that it is not a safe source. More
information about contaminants and their potential
health effects can be obtained by calling the Environmental
Protection Agency's Safe Drinking Water Hotline at
(800) 426-4791.
Please note that cryptosporidium and giardia are associated
with surface water supplies and are not commonly detected
in groundwater. As in previous years Daly City's wells
have never had a detected level of either of these
microbes.
Lead
Lead in amounts in excess of established action levels
in drinking water can cause delayed physical and/or
mental development in infants, and attention span
and learning deficits in children. In adults it can
cause kidney problems and possible high blood pressure.
Because of these concerns the EPA mandated in 1993
that lead and copper monitoring be conducted by all
large water systems. Daly City completed the required
monitoring and corrosion study in 1994. The results
of the study were well under any action levels and
met all quality standards. In 1998, under advisement
from the EPA, DHS required local water systems to
complete their studies. A joint effort was organized
by the SFPUC for collection and analysis of samples
by the member agencies. Since Daly City had previously
conducted the study, an agreement was reached with
DHS to do a special water quality study to determine
the aggressiveness (corrosivity) of our well water
and determine ways to meet the requirements for corrosion
control in our water system. The study was completed
in September 1999. Lead and copper are prevalent materials
used in fixtures and pipes. There was a time in the
past when pipes themselves were made of lead. Lead
and copper can be dissolved through contact with water.
The rate or amount of material that can be put into
solution is based on the corrosivity or aggressiveness
of the water. The goal of the EPA program is to find
the best way(s) to optimize water systems to lower
the aggressiveness of the water in that system.
The results of the second Daly City study indicated
that the well water offered a buffering effect that
lowered corrosivity of the water, and the blending
of SFPUC supplied water with our well water actually
lowered the corrosivity of the SFPUC water to optimum
levels.
Future Changes
Fluoridation
SFPUC has fluoridated their treated water for almost
50 years. Depending on your location in Daly City
you may receive all SFPUC supplied water and have
the full optimum determined fluoride content of 1
mg/L (parts per million). In other areas that receive
blended well and SFPUC water, you may be receiving
water with fluoride levels as low as 0.3 mg/L, since
we do not fluoridate our well water. Over the next
two years Daly City is anticipating adding systems
to fluoridate the well water blended at the City's
three pump stations.
Chloramination
One of the current goals of the EPA and DHS
is to lower disinfection byproducts in drinking water.
These are organic compounds formed by the breakdown
of chlorine as it oxidizes microbial material.
To reduce the level of these compounds, a small amount
of ammonia can be added which forms "chloramines".
These chloramines optimize the effect of the chlorine
by allowing it to exist longer in the water and break
down less than chlorine alone. The SFPUC is making
the switch within the next few years. The anticipated
date for this conversion is early 2003. At that time
Daly City will make the same modification to its system
to maintain a uniform disinfection process between
the SFPUC water and our blended well water.
People on dialysis or with other specific health needs
may need to alter the methods they use to prepare
water for treatment when the change to chloramination
takes place. Also there will be some changes necessary
for aquarium owners, as chloramines are toxic to fish.
Aquarium owners will need to fully de-chlorinate tank
make-up water Public notices with the necessary information
will be distributed preceding the actual change. And
the City will work with the Medical Community to fully
inform those residents at risk of adverse effects
prior to the change. This information will be sent
out in a timely manner, allowing you ample time to
make any changes if you are one of the few customers
that will be affected by the change. Switching to
chloramines has been very successful across the country
and the positive benefits far exceed the known potential
problems.
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