Water Quality

Water Quality

The City's raw water supply comes from Kaw Lake, which is located approximately ten miles east of Ponca City in Kay County. Raw water from Kaw Lake is transported to the City's treatment facility located at 1022 West Yost Road. In 2017, Stillwater's Water Treatment Plant (WTP) supplied more than 2.3 billion gallons of safe drinking water to Stillwater citizens, five rural water districts, and several mobile home communities in Payne and Noble Counties.

Water Treatment Process

Raw water is treated through physical and chemical processes. The physical processes we use include: mixing, flocculation, clarification and filtration. Chemicals are added to the process for various reasons:

  • Ferric Sulfate helps the fine particles combine into larger particles that become heavy and settle to the bottom of the settling basin.

  • Polymer is used as a coagulant aid.

  • Calcium Oxide (Lime) is a softening chemical that causes dissolved hardness particles to precipitate and settle to the bottom of the settling basin.

  • Carbon Dioxide is used to adjust pH and seize the softening process.

  • Ozone is used as a disinfection chemical and improves taste and odor.

  • Fluoride is added to the finished water to improve oral health.

  • Chloramines are used to provide a disinfection residual in the distribution system. Chloramines require the addition of both chlorine and ammonia separately.

WTP staff routinely collect and analyze water samples throughout the treatment process. For example, raw water turbidity is tested four times each day and finished water is tested six times each day. 

The Environmental Protection Agency and Oklahoma Department of Environmental Quality require routine monitoring for certain parameters. Results of these tests are submitted monthly to ODEQ. Some parameters listed below are analyzed less frequently than once per year, according to the required sampling schedule. For these parameters, the most recent data is reported.

It is reasonable to expect that all drinking water, including bottled drinking water, will contain at least small amounts of some elements. These may be microbes, organic chemicals, radioactive or other materials. It is important to remember that the presence of these elements does not necessarily pose a health risk.

The tables below show the results for parameters analyzed from January 1, 2017 to December 31, 2017.

2017 Annual Water Quality Report


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

  • Parts per billion (ppb) or Micrograms per Liter (µg/L) - One part of contaminant per billion parts of water.

  • Parts per million (ppm) or Milligrams per Liter (mg/L) - One part of contaminant per millions part of water.

  • No Detection (ND) - The contaminant was not detected in the sample.


Microbial Contaminants Violations
Turbidity None


Bacteriological Contaminants Violations
Coliform (TCR) None


Disinfection By-Products Rules Stage 2 Violations
Chlorine None
Total Trihalomethanes None
Haloacetic Ac None


Radionuclides Violations
Gross Alpha None
Gross Beta None
Radium 226+228 None
Uranium None


Organic Carbon Violations
Total Organic Carbon None

Lead and Copper (Regulated at Customers' Tap)

Parameter Action Level* 90% Sample Detected Violations
Lead 15ppb <0.005ppb None
Copper 1.3ppm 0.157ppm None

*Action Level - 90% of samples must be below this level

Inorganic Contaminants Date Samples Violations
Antimony 10/22/2015 None
Arsenic 10/22/2015 None
Barium 10/22/2015 None
Cyanide 10/26/2012 None
Fluoride 2017 None
NitrateNitrite 2017 None
Selenium 10/22/2015 None
Beryllium 10/22/2015 None
Cadmium 10/22/2015 None
Chromium 10/22/2015 None
Mercury 10/22/2015 None
Nickel 10/22/2015 None
Thallium 10/22/2015 None
Sodium 10/22/2015 None

Long Term 2 Enhanced Surface Water Treatment Rule (Raw Water Testing) 2016

Analyte / Unit Jan.13 Feb.10 Mar.9 Apr.13 May11 Jun.8 Jul.14 Aug.10 Sep.14 Oct.12 Nov.9 Dec.14
Cryptosporidium, oocysts / L ND ND ND ND ND ND ND ND ND ND ND ND
Giardia, cysts / L ND ND ND ND ND ND ND ND ND ND ND ND
E. Coli, MPD / 100mL 2.0 3.0 12.1 2.0 4.1 35.0 <1 <1 40.4 7.4 7.4 60.5
Turbidity / NTUs 19.1 19.9 11.0 7.12 10.8 63.5 40.52 24.3 128 44.1 19.6 8.1

Important Health Information

Some people may be more vulnerable to contaminants in drinking water than the general population. Immuno-compromised persons, such persons with cancer undergoing chemotherapy, persons who have undergone organ transplants, people 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. Environmental Protection Agency/Center for Disease Control publishes guidelines on appropriate means to lessen the risk of infection by cryptosporidium and other microbiological contaminants. These guidelines are available from the Safe Drinking Water Hotline at (800) 426-4791.

Additional Information about Lead

If present, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. Lead in drinking water is primarily from materials and components associated with service lines and home plumbing. We are responsible for providing high-quality drinking water, but we cannot control the variety of materials used in home plumbing components. You can minimize the potential for lead exposure by flushing your tap for 30 seconds to two minutes before using water for drinking or cooking. If you are concerned about lead in your water, you may wish to have your water tested. Information about lead in drinking water, testing methods and steps you can take to minimize exposure are available from the Safe Drinking Water Hotline at (800) 426-4791 or http://www.epa.gov/safewater/lead.

Content last reviewed 06.17.2020