2000

ANNUAL WATER
QUALITY REPORT
Water Quality Management Division

Tucson Water is pleased to
provide our customers with this
third Annual Water Quality
Report. The report will serve as a
reference with important
information on the quality of
water we deliver, provide you
with contacts and phone
numbers you may need from
time to time, and fulfill a federal
regulatory requirement to give
you annual information about
the source and quality of your
drinking water.

CLE RD
O RA

SKYLINE DR

RIV

ER RO
A

IRONWOOD HILLS

CRAYCROFT RD

INA RD

D

SNYDER RD

TANQUE

VERDE RD

GRANT RD
SPEEDWAY
BROADWAY
22ND STREET

KI

NN

AJO

HIG

VALENCIA RD

PIMA MINE RD

COUNTRY CLUB RD

Y
WA
NOGALES HIGH

WHERE DOES OUR DRINKING
WATER COME FROM?

IRVINGTON

HOUGHTON

AY
HW

RD

RD

KOLB RD

EY

MISS
ION RD

• Where does our drinking water
come from?
• What contaminants have been
detected in our drinking water?
• Detailed information on
detected contaminants.
• Definitions of technical and
regulatory terms used in the
report.
• Information on expected
drinking water contaminants.
• Were there any violations
of drinking water regulations?
• How is our drinking water
treated?
• Who can I contact for
more information?

If you are a non-English speaking resident, we recommend that you speak
with someone who understands the report. Call our Public Information
Office at 791-4331 for a copy of this report in Spanish. The format for this
report follows the guidelines set by the United States Environmental
Protection Agency (USEPA) as part of the Safe Drinking Water Act. The
USEPA requires all public water providers to deliver this information to
all customers on an annual basis in a single report that provides water
quality data to the public in an understandable manner.

SANDARIO RD

THIS REPORT CONTAINS THE
FOLLOWING INFORMATION:

In 2000, Tucson Water served about 675,000
people in the Tucson area. The water supply
came from approximately 190 groundwater wells located in and around the Tucson metropolitan area (see map).
In urban Tucson, most of the wells (also known as Points of Entry or POE) serve the neighborhood in which they
are located, with excess supply routed to reservoirs for use elsewhere in the system. Wells located outside the
urban core often deliver water to a single “collector” main prior to delivery to customers. In these cases, the
collector main is termed a “combined Point of Entry (POE)” to the drinking water system. The Tucson Water
system has three combined POEs: the Southern Avra Valley well field, the Santa Cruz well field, and the South
Side well field, which includes Tucson Airport Area Remediation Project (TARP).
1

WHAT CONTAMINANTS HAVE BEEN DETECTED IN OUR DRINKING WATER?
Tucson Water regularly samples the
drinking water that is delivered to
you. Much of this testing is required
by drinking water regulations. In
addition to this required monitoring,
we perform a great deal of
discretionary monitoring in order to
provide both Tucson Water staff and
customers
with
additional
information.
The table on the next page lists all
contaminants that were detected in
both the required and discretionary
drinking water monitoring.
Three inorganic contaminants of
special interest are arsenic, fluoride,
and nitrate. Fluoride and arsenic are
naturally occurring and tend to
increase as water is drawn from

greater depths. Nitrate on the other
hand is typically found in higher
concentrations near the surface of the
groundwater table because it is
frequently associated with fertilizer
use, septic tanks and other human
activities. Please see the Detected
Contaminants Table and the specific
explanations, which follow the table,
for more information.
It is important to remember that the
detection of a contaminant in
drinking water does not necessarily
represent a threat to public health.
Current technology allows water
utilities to detect extremely low
levels of contaminants in drinking
water. A detected result means a
concentration that is above the

minimum value that can be
measured by the laboratory. In most
cases, the minimum detectable level
of a contaminant is well below the
USEPA regulatory limit for that
contaminant. To compare the
detected amount with the amount
allowed by the USEPA, refer to the
Maximum Contaminant Level
(MCL) column in the table. (Because
the vast majority of regulated
contaminants were not detectable in
drinking water delivered by Tucson
Water, the non-detected results were
not included in this table. For a
complete list of all USEPA regulated
contaminants contact the USEPA at
1-800-426-4791 or visit the USEPA
website at www.epa.gov/safewater/
creg/html.

INFORMATION ON EXPECTED DRINKING WATER CONTAMINANTS
In 2000, groundwater was the source of all of the drinking water delivered by Tucson Water. All drinking water, including
bottled water, may reasonably be expected to contain at least small amounts of some contaminants. Tucson’s groundwater
contains dissolved minerals and organic compounds, which have been leached from the rock, sediments, and plant materials
through which the water traveled. One would expect to find beneficial minerals such as calcium and magnesium, harmless
minerals such as chloride, bicarbonate, and sulfate, and metals such as iron, copper, arsenic, and lead, which may be either
beneficial or harmless at low concentrations, but harmful at high concentrations. In addition to these naturally occurring
contaminants, our groundwater may contain contaminants resulting from human, industrial or domestic activities. For this
reason, water utilities must currently monitor for approximately 90 regulated and 48 unregulated contaminants.
The following language is required by the USEPA to appear in this report, some of which may not be applicable to deep
groundwater wells, the source of the Tucson Water supply:
Contaminants that may be present in a source water can include:
• Microbial contaminants, such as viruses and bacteria, which may come from sewage, agricultural livestock, 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.
In order to ensure that tap water is safe to drink, USEPA regulations limit the amount of certain contaminants in water
provided by public water systems. Food and Drug Administration regulations establish limits for contaminants in bottled
water that must provide the same protection for public health. Bottled water may come from either a surface water source or
groundwater source, and may be treated minimally or extensively. For information on the quality of your bottled water,
contact the water bottling company.

A SPECIAL NOTE TO AT-RISK POPULATIONS
While the Safe Drinking Water Act regulations are intended to protect consumers throughout their lifetime, some people
may be more vulnerable to infections from drinking water than the general population. These “at-risk” populations include:
immuno-compromised persons such as persons with cancer undergoing chemotherapy, people who have undergone organ
transplants, people with HIV/AIDS or other immune system disorders, and in some cases, elderly people and infants. These
people should seek advice about drinking water from their health care providers. USEPA/CDC guidelines on appropriate
means to lessen the risk of infection by cryptosporidium and other microbial contaminants are available from the USEPA’s
Safe Drinking Water hotline.
2

DETECTED CONTAMINANTS TABLE
Inorganics Contaminant
Arsenic, Total
Fluoride
Nitrate (as N)

Maximum Result
10 ppb
2 ppm
8.3 ppm

Range
< 1.5 — 10 ppb
< 0.1 — 2 ppm
0.34 — 8.3 ppm2

MCL
50 ppb
4 ppm
10 ppm

MCLG
None
4 ppm
10 ppm

Major Sources
Natural deposits
Natural deposits
Natural deposits; septic tanks; agriculture; sewage

Radiochemical Contaminant
Adjusted Gross Alpha
Radon Activity
Radium Activity, Combined
Uranium Activity

2.5 pCi/L
1420 pCi/L
0.2 pCi/L
5.1 pCi/L

< 0.5 — 2.5 pCi/L
< 20 — 1420 pCi/L
0.2 — 0.2 pCi/L
<0.5 — 5.1 pCi/L

15 pCi/L
No MCL
5 pCi/L
30 pCi/L

0 pCi/L
None
0 pCi/L
None

Natural deposits
Natural deposits
Natural deposits
Natural deposits

Volatile Organics Contaminant
Chloromethane

0.7 ppb

<0.5 — 0.7 ppb

No MCL

None

Dibromomethane

0.9 ppb

<0.5 — 0.9 ppb

No MCL

None

Ethylbenzene

1.1 ppb

<0.5 — 1.1 ppb

700 ppb

700 ppb

Methyl-tert-butyl Ether
Tetrachloroethene (PCE)
Total Xylenes

0.6 ppb
0.8 ppb
0.0092 ppm

<0.5 ppb — 0.6 ppb No MCL
< 0.5 — 0.8 ppb
5 ppb
< 0.0005 — 0.0092 ppm10 ppm

None
0 ppb
10 ppm

Rubber manufacturing; refrigerant; propellant
in polystyrene foam production
Fumigant for ground pest control; constituent of ethyl
gasoline
Solvent used in paint coatings; Component of aviation
and automotive gasoline
Fuel additive
Dry cleaning agent; degreaser
Solvent used in paint coatings, adhesives, and fuel

< 0.1 — 0.19 ppb
< 0.6 — 2.9 ppb
< 0.04 — 0.12 ppb

70 ppb
6 ppb
1 ppb

70 ppb
0 ppb
0 ppb

Herbicide used for weed control
Rubber and chemical manufacturing
Wood preservative

< 0.5
< 0.5
< 0.5
< 0.5
< 0.5

n/a
n/a
n/a
n/a
80 ppb

n/a
n/a
n/a
n/a
0 ppb

By-product of chlorination
By-product of chlorination
By-product of chlorination
By-product of chlorination
By-product of chlorination

MCLG

Major Sources

0
1.3 ppm

Corrosion of household plumbing systems
Corrosion of household plumbing systems

Synthetic Organics Contaminant— 1998
2,4-Dichlorophenoxy acetic acid 0.19 ppb
Di(2-ethylhexyl)phthalate
2.9 ppb
Pentachlorophenol
0.12 ppb
Trihalomethanes Contaminant
Chloroform
Bromodichloromethane
Bromoform
Chlorodibromomethane
Total Trihalomethanes (TTHMs)
Annual Average for TTHMS

0.5 ppb
1.5 ppb
4.2 ppb
3 ppb
6.9 ppb
2.2 ppb

— 0.5 ppb
— 1.5 ppb
— 4.2 ppb
— 3 ppb
— 6.9 ppb

Contaminant

No. of Samples Above 90th Percentile Value Action Level
the Action Level
Lead and Copper in Standing Water Samples — 1999
Lead
one
3.4 ppb
15 ppb
Copper
none
0.23 ppm
1.3 ppm
Contaminant

Month of Highest
Coliform Percentage

Number of Positive
Total # of Samples
MCL
Samples for the Month Collected for the Month

Inorganics
Total Coliform
2

May
1
246
11 positives
June
1
246
11 positives
A discretionary sample revealed 11 ppm nitrate, see additional information on detected contaminant.

MCLG

Major Sources

0
0

Naturally present in environment
Naturally present in environment

DEFINITIONS OF TECHNICAL AND REGULATORY TERMS
Action level. The concentration of a contaminant which, if
exceeded, triggers a treatment or other requirement which
a water system must follow.
Maximum Contaminant Level (MCL). The highest level of
a contaminant that is allowed in drinking water. MCLs
are set as close to the MCLGs as feasible using the best
available treatment technology. If a contaminant is
believed to cause health concerns in humans, then the
MCL is set as close as practical to zero and at an acceptable
level of risk. Generally, the maximum acceptable risk of
cancer is 1 in 10,000 with 70 years of exposure.
Maximum Contaminant Level Goal (MCLG). The level of a
contaminant in drinking water below which there is no
known or expected risk to health. MCLGs allow for a
margin of safety.
Parts Per Billion (ppb). Some constituents in water are
measured in very small units. One ppb equals one
microgram per liter. For example, one part per billion
equals: 2 drops of water in a 15,000 gallon backyard

swimming pool, one second of time in 31.7 years, or the
first 16 inches of a trip to the moon.
Parts Per Million (ppm). One ppm equals one milligram
per liter. One part per million equals: 1/4 cup of water in
a typical 15,000 gallon backyard swimming pool or one
second of time in 11.6 days.
Picocurie Per Liter (pCi/l). The quantity of radioactive
material in one liter which produces 2.22 nuclear
disintegrations per minute.
Point of Entry (POE). All water sources are monitored at
the point of entry to the distribution system before the
first customer but after any required treatment. For most
wells directly feeding the distribution system without
treatment, the POE is the well, but in a few cases where
the water from a number of wells is collected in a common
pipeline before delivery, the POE represents a number of
wells in a well field.
Treatment Technique. A required process intended to reduce
the level of a contaminant in drinking water.
3

DETECTED CONTAMINANTS: PERCENT OF POSITIVE SAMPLES FOR TOTAL COLIFORM

EPA Maximum Contamination Level is 5%
1997
1998
1999
2000

INFORMATION ON DETECTED CONTAMINANTS
Coliform bacteria are very commonly found in the
environment and in the digestive tracts of animals. While
rarely harmful, coliform bacteria in drinking water are
an indicator that the water may also contain harmful
microorganisms.

unexpected increase in well SC-006a, which serves about
330 customers located south of Hughes Access Road and
west of Nogales Highway. This well had a 50 percent
increase in nitrate within 30 days. When the 11 ppm
concentration test result was received, the well was
immediately closed, customers were notified and bottled
water provided until an alternate source of water could
be routed to this area. This was the only case nitrate was
above the 10 ppm standard. The next highest level for
nitrate was 8.3 ppm. Tucson Water performs extra
monitoring for wells high in nitrate for extra assurance
that action can be taken when approaching the MCL.
Nitrate in drinking water at levels above 10 ppm is a health
risk for infants of less than six months of age. High nitrate
levels in drinking water can cause blue baby syndrome.

Arsenic is a naturally occurring substance commonly
found in groundwater in the southwestern United States
that is known to cause cancer at high concentrations. EPA
is reviewing the drinking water standard for arsenic
because of special concerns that it may not be stringent
enough. To prepare for the lower standard Tucson Water
is participating in studies to determine the best treatment
process for removing arsenic from Tucson groundwater.
Tucson Water completed four quarters of arsenic
monitoring at all points of entry (POE) to determine the
impact of this new standard. The highest arsenic
concentration was 10 ppb. For more information and a
color-coded map indicating the arsenic concentrations in
our wells, please visit our website: www.ci.tucson.az.us/
water/.

Lead and Copper are naturally occurring metals, which
are generally found at very low levels in source waters.
However these levels can increase when water contacts
plumbing materials that contain lead or copper or brass.
Infants and young children are more vulnerable to lead
in drinking water than the general population. While
Tucson Water is well within standards, concerned
customers can take an extra precaution to protect children
from lead leached from new brass faucets by running the
water for a few seconds and using the water for something
other than drinking. This is especially important if the
water has been sitting in the pipes for a few hours or more.

Fluoride is an important naturally occurring mineral that
helps to form healthy teeth and bones. A concentration
of 0.8 ppm is considered optimum for Tucson. At
concentrations above 2 ppm, fluoride can cause mild
discoloration of teeth, and exposure at above the MCL of
4 can cause both severe discoloration of teeth and over
many years of exposure, bone disease.
Nitrate is a form of nitrogen and an important plant
nutrient. Nitrate values met standards except for an
4

Adjusted Gross Alpha is a measure of radioactivity due
to naturally occurring minerals in groundwater. The MCL
for gross alpha radioactivity is set at 15 picocuries per
liter (pCi/l). This excludes the radioactivity contributed
by either radon or uranium.

INFORMATION ON DETECTED CONTAMINANTS (CONTINUED)
refurbished water pressure tanks. These low
concentration releases from pressure tank coatings rapidly
decrease as the tank ages. One POE had ethylbenzene at
1.1 ppb (the MCL is 700ppb), and three POEs had total
xylenes of which 0.0092 ppm was the maximum (the MCL
is 10 ppm).

Radon is a naturally occurring radioactive gas that may
cause cancer, and may be found in drinking water and
indoor air. While ingesting radon in drinking water has
a small risk, inhaling radon is a primary health concern,
particularly for smokers or ex-smokers. Radon diffusing
up from the soil into homes and buildings is usually the
main source of radon in indoor air. Only about 1-2 percent
of radon in indoor air comes from drinking water.

Methyl-tert-butyl Ether (MTBE) was detected in only a
single well at the very low concentration of 0.6 ppb. MTBE
is a popular gasoline additive used to reduce air pollution.
EPA is currently reevaluating its use due to its threat to
water supplies. While MTBE is not thought to be a
significant health threat at low concentrations, it has a very
low taste and odor threshold and is difficult to remove
from drinking water supplies by treatment. Unlike most
VOCs, MTBE is very soluble in water. This property
allows it to move readily with percolating water and
contaminate groundwater much more readily than the less
soluble components of gasoline. MTBE does not appear
to present a major threat to Tucson’s groundwater
supplies.

If you are concerned about radon in your home, you
should test your house and install controls if you find a
level of 4 pCi/l or higher in your indoor air. For more
information, call USEPA’s Radon Hotline (800-SOSRADON) or visit the web site http://www.epa.gov/iaq/
radon/.
The USEPA does not currently have a final regulation for
radon in drinking water.
Extra radon monitoring was performed on the Tucson
Water wells in two quarters during 2000. Test results
indicate that, when compared with other communities
across the country, Tucson has fairly typical concentrations
for radon in the water supply. For more information on
radon, please visit our website: www.ci.tucson.az.us/
water/

Tetrachloroethylene (PCE) was detected in one well. The
detected amount was 0.8 ppb.
Synthetic Organic Contaminants (SOCs) are occasionally
detected in a monitoring sample, but the presence of an
SOC in the water produced by a potable supply well has
never been confirmed. The few occasions when SOCs
were detected can be attributed to contamination during
sampling, shipping, or in the laboratory. Tucson Water
was not required to sample for SOCs during 2000. The
detected SOCs shown in the table are from 1998.

Radium 226 and 228 are two radioisotopes of radium. The
combined amount of both currently cannot exceed an
MCL of 5 pCi/l.
Uranium is a metallic element, which is highly toxic and
radioactive. The USEPA has just set a new standard of 30
ppb or approximately 30 pCi/l for uranium, which water
systems must meet by December 2003.

Chloroform, Bromodichloromethane, Bromoform, and
Chlorodibromomethane are unregulated Volatile Organic
Contaminants that make up the contaminant group
known as total trihalomethanes. These compounds are
detected at very low concentrations in Tucson’s
chlorinated groundwater.

Volatile Organic Compounds (VOCs) include such
compounds as trichloroethylene (TCE) and
tetrachloroethylene (PCE). VOCs are volatile like alcohol
or gasoline and are made up of relatively small molecules,
which allows them to migrate readily through soils.
Solvents such as TCE and PCE have been commonly used
for cleaning machine parts, and for dry cleaning. These
contaminants are often associated with industrial
operations and landfills. Despite the vulnerability of
groundwater to such contamination, Tucson Water’s
potable supplies are virtually free of such contamination.

Total Trihalomethanes (TTHMs) are formed when chlorine
combines with naturally occurring organic material in
water. Since the level of organic matter in our
groundwater is extremely low, these compounds are
found at very low concentrations. Compliance with the
TTHM is based on the running average quarterly
concentration at 16 distribution monitoring points, (2.2
ppb for the year 2000). The compounds, which make up
the TTHMs, include: chloroform, Bromodichloromethane,
bromoform, and chlorodibromomethane. The highest
TTHM result in any system sample was 6.9 ppb and the
highest concentration for any of the four compounds was
4.2 ppb for bromoform. The standard is 80 ppb.

Chloromethane and Dibromomethane are industrial
solvents and were both detected at 0.7 ppb and 0.9 ppb
respectively.
Ethylbenzene and Xylenes are residual solvents, typically
associated with the coatings used to protect new or
5

MONITORING WAIVERS

HOW IS OUR DRINKING WATER TREATED?

The Arizona Department of Environmental Quality, the
regulatory agency for all public water suppliers in
Arizona, grants waivers for certain monitoring
requirements during a year. Waivers are granted for
specific contaminants if previous monitoring results, and
the land uses within a half-mile radius of the well, allows
ADEQ to conclude that the risk of contamination by a
specific substance is very low.

The groundwater delivered by Tucson Water meets all
drinking water standards without treatment, with the
exception of the water supplied from the Tucson Airport
Area Remediation Project (TARP) wells. However,
approximately 0.8 parts per million (ppm) of chlorine is
added to the drinking water supply at well sites, and
approximately 1 ppm is added to reservoirs and other
facilities to provide assurance that water delivered to
customers will remain free of microbiological
LATE MONITORING AND REPORTING
contamination. This also ensures that the water meets
At the end of each year Tucson Water conducts an internal microbiological drinking water standards from the time
audit of compliance monitoring records to verify that all it is pumped from the ground until it reaches the
required monitoring has been completed and reported to customer’s tap.
the State. The 2000 audit revealed that Tucson Water was
late on one occasion in reporting results to the State: The MORE ABOUT TARP
reports on 13 microbiological samples taken in March 2000 The TARP program was developed in order to clean and
were due to ADEQ by April 10, 2000, but were sent on make beneficial use of water contaminated with the
April 17, 2000. A public notification for this violation was industrial solvent trichloroethylene (TCE). Tucson Water
published in The Arizona Daily Star and The Tucson Citizen operates TARP under an agreement with the USEPA and
newspapers. As stated in the public notice, this was a other industrial and governmental agencies, which pay
reporting error only and it does not represent any threat for operation of the TARP program.
to public health.
Nine wells extract the contaminated water and deliver it
through a pipeline to a treatment plant that removes the
TCE from the water. The TARP treatment plant uses an
“air stripping” process which forces volatile contaminants
such as TCE to evaporate from the water into air. The air
is then passed through activated carbon filters, which
removes the airborne TCE. The TARP plant treats
approximately 7.3 million gallons of water per day.
During 2000, this plant treated a total of approximately
2.7 billion gallons of water.

WHAT ABOUT CAP WATER?
City of Tucson has rights to approximately 139,000 acrefeet of Colorado River water per year delivered through
the Central Arizona Project (CAP). However, no CAP
water was delivered to drinking water customers in 2000.
At the Clearwater Renewable Resource Facility located
in Avra Valley, Tucson Water is recharging a portion of
the City’s available CAP supply by delivering the river
water to shallow basins and allowing the water to
percolate (or recharge) naturally through the earth to reach
and blend with the groundwater below. Tucson Water
began delivery of this blend of recharged CAP water and
groundwater in May 2001. In the early years of delivery,
this new source will primarily be Avra Valley (AV)
groundwater. Over time, it will contain an increasing
percentage of recharged CAP water. During the year 2000,
Tucson Water served a mixture of (AV) groundwater and
recharged CAP water to selected volunteer neighborhoods
in Tucson, which approximates what this blend will be
like in 8 to 10 years. Information on the quality of this
blend is not contained in this report, but is available on
Tucson Water’s web site.

This treated water has non-detected levels of TCE. The
treated water has been tested on a weekly basis since the
start of operations in 1994. The cleaned water flows into
the Tucson Water system and is delivered to customers as
part of the drinking water supply. This water accounts
for approximately 8 % of water served on a daily basis by
Tucson Water.

6

WHO DO I CONTACT FOR MORE INFORMATION?
For more information on this Tucson Water report
contact Tom Jefferson with the Water Quality
Management Division. Call 791-5252 or e-mail your
questions to tjeffer1@ci.tucson.az.us.
The Water Quality Management Division also
publishes an Annual Microbiological Water Quality
report detailing the results of monthly distribution
system monitoring. Call 791-5252 for more
information.
In 2000, Tucson Water also collected additional
monthly water quality data. The results of this
additional monitoring are available on the Tucson
Water web page, www.ci.tucson.az.us/water/, and
the water quality phone line.
In early 2001 Tucson Water and a number of partners
were awarded a $400,000 grant by the USEPA
Environmental Monitoring for Public Access and
Community Tracking (EMPACT) program. The funds
will be used to support additional distribution of
water quality information to the community.

Tucson Water
P.O.Box 27210
Tucson, AZ
85726-7210

TELEPHONE NUMBERS:
Tucson Water Quality Automated phone line: 791-4227
Tucson Water Public Information Office: 791-4331
Tucson Water Quality Management Division: 791-5252
Tucson Water Customer Advocate: 791-5945
Tucson Water Customer Service/Billing: 791-3242
Tucson Water 24-hour Emergency: 791-4133
United States Environmental Protection Agency Safe
Drinking Water Hotline: 1-800-426-4791
USEPA Website: www.epa.gov/safewater/
Si usted desea este documento escrito en español,
por favor, llame al 791-4331.
City of Tucson TTY#: 791-2639
The Report Cost: The approximate cost for printing
and mailing each of these individual reports
was 30 cents.
7

PIO 5/01