Water Quality
Last year, we monitored your drinking water for more than 80 possible contaminants.  This Consumer Confidence Report is a snapshot of the quality of the water that we provided last year.  Included are details about where your water comes from, what it contains, and how it compares to Environmental Protection Agency (EPA) and state standards.  We are committed to providing you with information because informed customers are our best allies.

Water Source
We serve more than 4,781 customers an average of 1,353,300 gallons of water per day.  We get our water from surface water sources.  The state has performed an assessment of our source water and they have determined that the relative susceptibility rating for the Mid-Dakota Rural Water public water supply system is medium.

For more information about your water and information on opportunities to participate in public meetings, call (605) 945-2239 and ask for Bill Sarringar.

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Additional Information

The 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 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 naturallys-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 by-products 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, EPA prescribes regulations which limit the amount of certain contaminants in water provided by public water systems.  FDA regulations establish limits for contaminants in bottled water which must provide the same protections for public health.

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 Environmental Protection Agency's Safe Drinking Water Hotline (800-426-4791).

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, persons 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 guideline on appropriate means to learn the risk of infection by Cryptosporidium and other microbial contaminants can be obtained by calling the Environmental Protection Agency's Safe Drinking Water Hotline (800-426-4791).
 

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Detected Contaminants

The table entitled "2004 Water Quality Test Results" lists all the drinking water contaminants that we detected during the 2004 calendar year.  The presence of these contaminants in the water does not necessarily indicate that the water poses a health risk.  Unless otherwise noted, the data presented in this table is from testing done January 1 - December 31, 2004.  The state requires us to monitor for certain contaminants less than once per year because the concentrations of these contaminants are not expected to vary significantly from year to year.  Some of the data, though representative of the water quality, is more than one year old.

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WHAT TREATMENT DOES OUR WATER RECEIVE?

The water we pump from the Oahe Reservoir is surface water that comes from the Missouri River and the watershed pertaining to the Oahe Reservoir.  As water travels over the surface of the land or through the ground, it dissolves naturally occurring minerals and can pick up substances resulting from the presence of animals or from human activity.  Too much of any substance, either naturally occurring or resulting from human activity, can be considered a contaminant.

After passing through a screen that keeps out the larger debris (driftwood, fish, etc.), water from the Oahe Reservoir is pumped to our raw water storage tanks overlooking the reservoir.  From there, the water travels via gravity flow to our water treatment plant.  On the way, it passes through our chemical feed building, which stands on the same property as our raw water storage tanks.

In the chemical feed building, potassium permanganate and chlorine may be added to the water.  Potassium permanganate is used to remove iron and manganese and has some taste and odor-control properties.  The removal of iron and manganese helps to prevent laundry and plumbing fixtures from being stained.  Mid-Dakota water has very low levels of iron and manganese when compared to most ground water in the surrounding area.  Chlorine is added when the temperature is cold and more contact time is needed to disinfect the water.  State surface water treatment rules require that disinfectants be in contact with the water for a certain period of time, depending on water temperature and pH.

As water enters the treatment plant, a coagulant (ferric sulfate or, in our case, aluminum sulfate) and, at times, a polymer are added to form a pin floc.  Flocculation is the process whereby small particles of impurities in the raw water "floc" together with the coagulant and polymer, forming larger particles that are easily filtered out.  Chlorine can also be added at this point. 

The water then enters flocculation basins where the pin floc is formed.  These basins also provide contact time with the disinfectant and the water.  Next, the water passes through media filters, which remove the pin floc particles, and heads to the clearwell.

On its way to the clearwell, chlorine is added to adjust the disinfectant residual for the distribution system.  Fluoride is added for strong teeth.  Caustic soda, a sodium-based chemical, is added to stabilize the water to prevent the water from corroding or scaling the distribution piping.  Ammonia is added for the conversion of the free chlorine residual to a combined chlorine residual (chloramines) to minimize disinfection by-products and to form a more stable, longer-lasting disinfectant.  To further explain, the ammonia combines with any free chlorine in the water to form chloramines.  If ammonia wasn't combined with the chlorine, chlorine could combine with organic matter in the water and form trihalomethanes (THMs) in excess of EPA standards.  Some studies suggest THMs increase the risk of cancer.   A longer-lasting disinfectant is needed to maintain a chlorine residual in our large distribution system.  Chloramine disinfection is more practical than ozone.  With ozone, there is no residual disinfectant for the distribution system and it is expensive to generate.

From the clearwell, water is pumped throughout the distribution system.

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DEFINITION OF TERMS

These definitions are provided to assist you in understanding our water quality test results and the following discussion of the results.

ACTION LEVEL (AL) - The concentration of a contaminant which, if exceeded, triggers treatment or other requirements which a water system must follow.

TREATMENT TECHNIQUE (TT) - A required process intended to reduce the level of a contaminant in drinking water.  For turbidity, 95% of sample must be less than 0.3 NTU.

MAXIMUM CONTAMINANT LEVEL (MCL) - This is 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.

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. 

NOTE: MCLs are set at very stringent levels.  To understand the possible health effects described for many regulated contaminants, a person would have to drink 2 liters of water every day at the MCL level for a lifetime to have a one-in-a-million chance of having the described health effect.

Measurements -
pCi/l = picocuries per liter (a measure of radioactivity)                 ppb = parts per billion                                                                            ppm = parts per million or milligrams per liter (mg/l)                      NTU = nephelometric turbidity unit                                           MFL = million fibers per liter                                                             ppq = parts per quadrillion, or picograms per liter                       mrem/year = millirens per year (a measure of radiation absorbed by the body)

SUMMARY OF 2004 TEST RESULTS

Last year we monitored your drinking water for more than 80 substances.  Of these substances, only the 12 substances shown in the table were detected.  Our water in 2004 was in compliance with all U.S. EPA and state water quality standards.

Arsenic, barium, chromium, and selenium are all substances that are naturally occurring in the rocks and soil within the Missouri River watershed.  These four substances are at levels well below the highest level allowed by EPA.

As of October 31, 2001, the EPA has implemented a 10 ppb standard for arsenic.  Some people who drink water containing arsenic in excess of the MCL over many years could experience skin damage or problems with their circulatory system and may have an increased risk of getting cancer.

Chloroform, bromodichloromethane, and dibromochloromethane are three chemicals of a group of four chemicals called trihalomethanes (THMs).   THMs are produced in chemical reactions that take place in the water after chlorine is added.  Some people who drink water containing THMs in excess of the MCL over many years may experience problems with their liver, kidneys, or central nervous systems and may have increased risk of getting cancer.  The level of our THMs measured in 2004 is below the highest level allowed by EPA.

Halocetic Acids (HA) is also a by-product of chlorination, and people who drink water containing HA in excess of the MCL over many years have an increased risk of cancer.

Turbidity is a measure of the cloudiness of the water.  We monitor it because it is a good indicator of the effectiveness of our filtration system.  Our turbidity levels measured in 2004 were below the highest level allowed by EPA.  Fluoride is naturally present at low levels in our water.  We add fluoride to the water to promote healthy teeth.