Quality is the mission

Founded as an independent, municipal agency in 1918, Denver Water's goal always has been to produce a safe, dependable water supply and deliver it to metro homes and businesses at the lowest possible cost. Over the years, the water department has maintained a tradition of excellence that has kept pace with advancements in technology, increased public scrutiny and the intense demands of a growing city.

We've never violated a health standard. Since inception, the department has been treating and testing its water, and our findings always have been available to the public. This publication is Denver Water's annual summary of where your water comes from, what's in it, and how we treat, protect and deliver drinking water. We've also compared our test results with federal and state regulations, and we're pleased to report that Denver Water's record remains unblemished.

Denver Water hasn't faltered in its mission, in spite of impacts from the historic drought and wildfires on our watershed during the past several years. The department operates its reservoirs and dams to maximize best use of its supplies in terms of both quality and quantity. Denver Water continues with projects to prevent sediment from the fires reaching reservoirs as well as comprehensive testing of sources in the watershed by the Water Quality Lab.

All the department's facilities are under strict security, and we monitor Denver's water supply every step of the way. Analysts regularly take test samples at many remote sites and our caretakers watch over mountain sources to head off any problems long before they reach treatment plants in the city.

When you live in a semi-arid region and bring drinking water to more than a million people, you want to be certain there is enough to go around and that it is of the highest quality. That's a big job for Denver Water's 1,000 employees. Our Water Quality Lab keeps an eye on quality through both its field staff and data sent from 15 automated monitoring stations in the metro area. The Lab throughout 2003 conducted 40,639 microbiological and chemical tests from 11,996 samples. Denver Water treated 65.4 billion gallons of water last year, an average of 175 million gallons daily.

Notes about water

ALL DRINKING WATER, including bottled water, might reasonably be expected to contain at least small amounts of some contaminants. The presence of contaminants does not necessarily indicate that the water poses a health risk. Immunocompromised individuals – such as persons with cancer undergoing chemotherapy, persons who have undergone organ transplants, those with HIV-AIDS or other immune system disorders, and some elderly and infants – can be particularly at risk of infections. These people should seek advice about drinking water from their health care providers. For more information about contaminants and potential health effects, or to receive a copy of the U.S. Environmental Protection Agency and the U.S. Centers for Disease Control guidelines on appropriate means to lessen the risk of infection by cryptosporidium and microbiological contaminants, call the EPA Safe Drinking Water Hotline at 1-800-426-4791.

SOURCES OF DRINKING WATER – both tap 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 might be present in source water include:

• Microbial contaminants, such as viruses and bacteria that 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 storm water runoff, industrial or domestic wastewater discharges, oil and gas production, mining or farming.
• Pesticides and herbicides that may come from a variety of sources, such as agriculture, urban storm water runoff and residential uses.
• Organic chemical contaminants, including synthetic and volatile organic chemicals, which are byproducts of industrial processes and petroleum production, and also may come from gas stations, urban storm water runoff and septic systems.
• Radioactive contaminants, which can be naturally occurring or be the result of oil and gas production and mining activities.

The Treatment Process

1 The treatment process consists of five steps – coagulation, sedimentation, filtration, corrosion control and disinfection. First, raw water from terminal reservoirs is drawn into mixing basins at our treatment plants, where we add alum and polymer...

2 ... That causes small particles to adhere to one another, making them heavy enough to settle into a basin from which sediment is removed. The water is then filtered through layers of fine, granulated material, either sand, coal or both, depending on the treatment plant...

4 ... Denver Water carefully monitors the amount of chlorine added to maintain quality of water at the farthest reaches of the system. Fluoride occurs naturally but is also added to treated water, and pH is maintained by adding alkaline substances to reduce corrosion in the distribution system and your home or business.

3 ... As smaller, suspended particles are removed, turbidity diminishes and clear water emerges. Finally, as protection against any bacteria and viruses that might remain, chlorine and ammonia are added before the water flows to underground reservoirs throughout the metro distribution system and into your home or business...

Crypto and Giardia: The search goes on

Denver Water has tested for Cryptosporidium and Giardia in both raw and treated water for more than 15 years and has never detected a viable indication of either in drinking water.

Crypto and Giardia are microscopic organisms that, when ingested, can result in diarrhea, cramps, fever and other gastro-intestinal symptoms. Crypto and Giardia must be ingested to cause disease, and they can be spread through means other than drinking water.

Most people readily recover from the symptoms, which can cause more serious illness in people with compromised immune systems. The organisms are in many of Colorado's rivers and streams and come from animal wastes in the watershed. Crypto and Giardia are removed by effective filtration at the treatment plant. Disinfectants also kill Giardia.

Recycling's story: Purple pipes and prose

Denver Water constantly looks for ways to conserve and extend supplies. We don't expect to run out, but we're getting into the business of treating wastewater and recycling it to make sure we don't. With its new wastewater recycling treatment plant, Denver Water reclaims water it owns that used to be lost down the South Platte River, extending current supplies farther into the future.

The reclaimed water isn't up to drinking water standards, but is treated to a high, nonpotable quality suited for irrigation, industrial applications, lakes in parks and wildlife preserves. It's safe for incidental body contact for both humans and pets and there has never been a reported illness associated with intended uses of recycled water. Purple pipes and fixtures signal recycled water.

Tests of the water are conducted daily by the Water Quality Lab and plant operators before it is treated and after it is in the system. The results are submitted to the state health department and are available to the public through Denver Water.

The system serves customers along a corridor extending 10 miles from the plant north of the city to Washington Park. Xcel Energy's Cherokee power plant uses recycled water for cooling purposes. Three small parks, a school, the zoo and Park Hill and City Park golf courses apply recycled water for irrigation. City Ditch returns the recycled water northward by channeling it to the lakes in Washington Park and City Park for both irrigation and aesthetics. Expansion will include more customers, notably the Stapleton and Lowry development sites and the wildlife refuges at the Rocky Mountain Arsenal.

Our recycling system is a new water supply project. At full capacity in 2011, the plant will produce up to 17,660 acre feet of water a year, or enough to fill a small reservoir. That will free up enough resources to serve potable water to 35,000 households. When both phases of the $164 million system are in place, the plant will be able to reclaim up to 5.5 billion gallons of water yearly.

Regulated at the Treatment Plant

Metals
Barium
in parts per million (ppm)

No

Monthly

2

2

0.044

0.015 - 0.053

Erosion of natural deposits; discharge of drilling wastes

Radiological
Beta/Photon emitters
in PicoCuries per Liter¹

No

Quarterly

n/a²

50³

2.8

n/d⁴

Decay of natural and man-made deposits

Uranium
in parts per billion (ppb)

No

Quarterly

n/a

30

n/d

n/d

Erosion of natural deposits

Inorganics
Fluoride
in ppm

No

6 times daily

4

4⁵

0.91

0.21 - 1.77

Erosion of natural deposits; water additive that promotes strong teeth

Nitrate
in ppm

No

Monthly

10

10

0.26

0.07 - 0.47

Erosion of natural deposits; leaching from septic tanks, sewage

Organics
Total Organic Carbon
as removal ratio

Notes
* MCLG and MCL: Maximum Contaminant Level Goal and Maximum Contaminant Level.
1. PicoCuries per liter.
2. Not applicable.
3. Four (4) milliroentgen equivalent man/year (equivalent dose) Trigger Level.
4. Non-detect: Laboratory analysis indicates that the constituent was not present.
5. Two (2) is the Secondary Maximum Contaminant Level, which is not enforceable. Exceeding the Fluoride Secondary Maximum Contaminant Level of two milligrams per liter triggers public notification.
6. Treatment Technique: a required process intended to reduce the level of a contaminant in drinking water.
7. Lowest running annual removal ratio.

Regulated in the Distribution System

Substance

Violation

Sampling Period

MCLG*

MCL*

Denver's Average

Range of Detections

Sources of Substances

Organic Disinfection
By-Products (DBPs)
Total Trihalomethanes¹
in ppb

No

Monthly

0

80

33

14 - 69

Haloacetic Acids (HAA₅)
in ppb

No

Monthly

n/a

60

20

7 - 58²

By-product of
drinking water chlorination

Microbiological
Total Coliform
as Absent or Present

No

Daily

0

5%³

0.55%⁴
 June '03

0.16%⁵

Naturally present
in the environment

Disinfectant
Cholaramine as Cl₂
in ppm

No

12 times
daily

n/a

4⁶

1.22

0.14 - 2.04

Drinking water disinfectant
used to kill microbes

Unregulated Contaminants¹

Substance

Violation

Sampling Period

MCLG*

MCL*

Denver's Average

Range of Detections

Sources of Substances

Organic Disinfection
By-products (DBPs)
Bromodichloromethane
in ppb

No

Monthly

n/a

n/a

8.0

0.8 - 13.0

Components of TTHM
(See chart above), a by-product
of drinking water chlorination

Chlorodibromomethane
in ppb

No

Monthly

n/a

n/a

2.5

n/d - 4.2

Chloroform
in ppb

No

Monthly

n/a

n/a

29.3

5.4 - 57.0

Chloral hydrate
in ppb

No

Monthly

n/a

n/a

3.0

0.5 - 6.4

By-products of
drinking water chlorination

Chloropicrin
in ppb

No

Twice Annually

n/a

n/a

0.6

n/d - 1.0

Cyanogen chloride
in ppb

No

Annually

n/a

n/a

10.3

6.3 - 18.0

Haloacetonitriles (HAN)
in ppb

No

Twice Annually

n/a

n/a

1.2

n/d - 3.1

Haloketones (HK)
in ppb

No

Twice Annually

n/a

n/a

1.2

0.5 - 2.4

Total Organic Halides (TOX)
in ppb

No

Annually

n/a

n/a

181

143 - 234

Inorganics
Sulfate
in ppm

No

Monthly

250

250²

60.4

16.1 - 75.3

Naturally present
in the environment

Regulated at the Customer's Tap¹

Substance

Violation

Sampling Period

MCLG*

Action Level²

90th Percentile Value

No. of Samples Exceeding AL

Sources of Substances

Inorganics
Lead
in ppb

No

Triennially

0

15

9

1 out of 51

Corrosion of household plumbing

Notes:
1. Lead isn't found in Denver's treated water. However, it might be present in a home's or business's plumbing. Because Denver Water has consistently been below lead and copper Action Levels, the state health department permits reduced monitoring once every three years. The next sampling for lead and copper will be in 2005. The figures in this report are from 2002.
2. Action level: Concentration of a contaminant that, if exceeded at the 90th percentile, triggers treatment or other requirements that a water system must follow.

Denver Water's Collection System

Fed by mountain runoff

Denver's drinking water comes from rivers, lakes, streams, reservoirs and springs fed by high-quality mountain snow runoff. The water comes entirely from surface sources over a watershed that covers 3,100 square miles on both sides of the Continental Divide. The farthest reaches of this system are more than 105 miles away, and the water is diverted and delivered to our treatment plants in the city by gravity through a complex system of streams, canals and pipes. Even though the water originates in pristine areas in the mountains, our strict quality control includes watershed protection. Denver Water employees who live and work throughout our watershed maintain continual surveillance of the water supply.
 

Sources of our water...
  are the South Platte River and its tributaries, the streams that feed Dillon Reservoir and the creeks and canals above the Fraser River. Mountain water is stored in six reservoirs – Antero, Eleven Mile, Cheesman, Dillon, Williams Fork and Gross – before it is sent to three treatment plants in the city. Prior to treatment, the water flows into three 'terminal' reservoirs where access is limited to further ensure the quality of the water. Last year, we also drew water out of Chatfield Reservoir.

Denver Water's three treatment plants...
 – Foothills, Marston and Moffat – are constantly maintained, evaluated and upgraded to stay abreast of advancements in technology and governmental regulations. After treatment, drinking water is fed by both gravity and pumps to a system of underground, clear-water reservoirs and then to your home or business. Some 2,500 miles of pipe carry water to Denver Water customers.

Some of the terms, abbreviations and symbols contained in this report are unique to the water industry and might not be familiar to all customers. In addition to explanations included in the footnotes to our Water Quality Roundup and other features on the other side, below are definitions to some other key terms:

Contaminant: A potentially harmful physical, biological, chemical or radiological substance.
Maximum Contaminant Level (MCL): Highest level of a contaminant allowed in drinking water. MCLs are set as close to the Maximum Contaminant Level Goal as feasible using the best available treatment technology.
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 million (ppm): Equivalent to milligrams per liter. One ppm is comparable to one drop of water in 55 gallons.
Parts per billion (ppb): Equivalent to micrograms per liter. One ppb is equivalent to one drop of water in 55,000 gallons.
PicoCuries per liter (pCi/L) and 4mrem/yr: Measures of radioactivity. Four milliroentgen equivalent man/year is a maximum contaminant level standard based on dosage; equivalent to about 50 picoCuries per liter.
Secondary Maximum Contaminant Level (SMCL): Non-enforceable, recommended limits for substances that affect the taste, odor, color or other aesthetic qualities of drinking water, rather than posing a health risk.
Maximum Residual Disinfectant Level (MRDL): Highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.
Maximum Residual Disinfectant Level Goal (MRDLG): Level of a drinking water disinfectant below which there is no known or expected health risk. MRDLGs do not reflect benefits of the use of disinfectants to control microbial contaminants.