2023 Drinking Water Quality Report

Carson & Underwood Water Systems

Bear Creek Dam Carson, WA
Spanish (Español) – Este informe contiene informacion muy importante sobre la calidad de su agua potable. Por favor lea este informe o comuniquese con alguien que pueda traducir la informacion.

Do I need to take special precautions?

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, 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’s (EPA) /Centers for Disease Control (CDC) guidelines on appropriate means to lessen the risk of infection by Cryptosporidium and other microbial contaminants are available from the Safe Water Drinking Hotline, call our hotline at (800) 426-4791.

What is this report?

We are pleased to present this year’s Annual Water Quality Report (Consumer Confidence Report) as required by the Safe Drinking Water Act (SDWA). This report is designed to provide details about where your water comes from, what it contains, and how it compares to standards set by regulatory agencies. This report is a snapshot of last year’s water quality. We are committed to providing you with information because informed customers are our best allies.

This year, you are likely reading the report online, rather than the traditional paper copy sent by mail. The Environmental Protection Agency changed the requirements to allow utilities to communicate this important information digitally. Customers are still able to request a paper copy by calling (509) 427-5126 or emailing Skamania PUD.

Lead Service Line Identification

meter and service line graphic In 2021, the U.S. Environmental Protection Agency (EPA) announced new revisions to the Lead and Copper Rule (LCR), the first significant changes in over 30 years. The EPA’s new rule, referred to as the Lead and Copper Rule Improvements (LCRI), aims to strengthen the LCR to better protect children and communities from the risks of lead exposure. One of the EPA identified priority improvements for the LCRI is proactive and equitable lead service line replacement (LSLR). Compliance with the LSLR provisions requires the PUD to create an inventory of water system connections identifying any lead service lines in need of replacement prior to the October 16, 2024 deadline.

For the Carson and Underwood water systems, the service line ownership is split meaning that the system (PUD) owns the portion up to the meter and the customer owns the portion of the service line from the meter to the house.

To complete a service line inventory of both water systems, the PUD will use a variety of methods including historical records review, identifying service line materials during normal operations, and service line investigations. If any lead service lines are identified, a plan for replacement of those lines will be prepared and submitted to the Department of Health.

While the PUD has no knowledge of any lead in our water systems, we consider compliance with the LCRI an important step in protecting our customers drinking water quality.

Where does my water come from?


water sytemCarson Water System has two sources of water; surface water from Bear Creek and groundwater from the Industrial Site Well located north of Carson on Old State Road.

Your Bear Creek surface water is treated in a “treatment train” (a series of processes applied in a sequence) that includes coagulation, flocculation, sedimentation, filtration, and disinfection. Coagulation removes dirt and other particles suspended in the source water by adding chemicals (coagulants) to form tiny sticky particles called “floc,” which attract the dirt particles. Flocculation (the formation of larger flocs from smaller flocs) is achieved using gentle, constant mixing. The heavy particles settle naturally out of the water in a sedimentation basin. The clear water then moves to the filtration process where the water passes through anthracite, sand, and garnet that remove even smaller particles. A small amount of chlorine is used to kill bacteria and other microorganisms (viruses, cysts, etc.) that may be in the water before water is stored and distributed to homes and businesses in the community.

Your Industrial Site ground water is treated by disinfection. Disinfection involves the addition of chlorine to kill dangerous bacteria and microorganisms that may be in the water. Disinfection is one of the major public health advances of the 20th century.


The Underwood Water System uses groundwater from Galligan Springs, Shaddox Springs, and Galligan Well located north of SR 14 at an elevation of 350 feet. The water is then pumped 925 feet to serve the community of Underwood. Like the Industrial Site, water treatment is provided by chlorination.

Source Water Assessment

Washington’s Source Water Assessment Plan (SWAP) is available at Washington State Department of Health website. The susceptibility rating is an assessment of the delineated area around the listed water sources through which contaminants, if present, could migrate and reach our source water. By default, the DOH assigns a susceptibility rating of “high” for all springs and surface water sources.

Source & Susceptibility Rating Table
SourceSusceptibility Rating
Bear Creek (Carson)High
Industrial Well (Carson)Moderate
Calligan Springs (Underwood)High
Galligan Well (Underwood)Low
Shaddox Springs (Underwood)High

Substances Expected To Be in Drinking Water

glass of waterDrinking 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 EPA Safe Drinking Water Hotline, call the Safe drinking Water hotline at (800) 426-4791.

The sources of drinking water (both tap water 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. The following substances may be present in source water (drinking water quality is determined by testing for these contaminants).

In order to ensure that tap water is safe to drink, EPA prescribes regulations that limit the amount of certain contaminants in water provided by public water systems. Food and Drug Administration (FDA) regulations establish limits for contaminants in bottled water which must provide the same protection for public health.

Contaminants Table
Types of ContaminantsDescription
Microbial Contaminants
(Such as viruses, parasites and bacteria)
May come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.
Inorganic Contaminants
(Such as salts and metals)
Can occur naturally or may result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining, and farming.
Pesticides and HerbicidesMay come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses.
Organic Chemical Contaminants
(Including synthetic and volatile organic chemicals)
By-products of industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff, and septic systems.
Radioactive ContaminantsCan be naturally occurring or the result of oil and gas production and mining activities.

Water Quality Data

young girl drinking from a water fountainThe Water Quality Table on the next page lists all the drinking water contaminants that we detected during the calendar year of this report. Although many more contaminants were tested, only those substances listed below were found in your water. All sources of drinking water contain some naturally occurring contaminants. At low levels, these substances are generally not harmful in our drinking water. Removing all contaminants would be extremely expensive, and in most cases, would not provide increased protection of public health. A few naturally occurring minerals may improve the taste of drinking water and have nutritional value at low levels.

Unless otherwise noted, the data presented in this table is from testing done in the calendar year of the report. The EPA or the State requires us to monitor for certain contaminants less than once per year because the concentrations of these contaminants do not vary significantly from year to year, or the system is not considered vulnerable to this type of contamination. As such, some of our data, though representative, may be more than one year old. In this table you will find terms and abbreviations that might not be familiar to you. To help you better understand these terms, we have provided the definitions.

ppmParts per million, or milligrams per liter (mg/L)
ppbParts per billion, or micrograms per liter (μg/L)
pCi/LPicocuries per liter (a measure of radioactivity)
NDnot detected
NTUNephelometricTurbidity Units. 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.
MCLGMaximum Contaminant Level Goal: 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.
MCLMaximum Contaminant Level: 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.
TTTreatment Technique: A required process intended to reduce the level of a contaminant in drinking water.
MRDLGMaximum Residual Disinfection Level Goal: The level of a drinking water disinfectant below which there is no known or expected risk to health.
MRDLMaximum Residual Disinfectant Level: The highest level of a disinfectant allowed in drinking water.
MPLState Assigned Maximum Permissible Level
Sampling Schedule
Chlorine residualContinuous monitoring
TurbidityContinuous monitoring
pHContinuous monitoring
Total coliform bacteriaMonthly
Disinfection by-productsQuarterly (Carson), Annually (Underwood)
CopperEvery 3 years
LeadEvery 3 years
PesticidesEvery 3 years
Volatile organic compoundsEvery 3 years (Carson) Every 6 years (Underwood)
RadionuclidesEvery 6 years
AsbestosEvery 9 years
HerbicidesEvery 9 years
Inorganic chemicalsEvery 9 years

Lead in Drinking Water

test tubeIf 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. The Carson and Underwood Water Systems have never used lead service lines. Homes built before 1987 are more likely to have lead plumbing. Some faucets and certain kinds of solder could also have lead in them, even those installed recently. When your water has been sitting for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to 2 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 on lead in drinking water, testing methods, and steps you can take to minimize exposure is available from the Safe Drinking Water Hotline or at United States Environmental Protection Agency Website.

Lead & Copper Monitoring Results
Sampling ScheduleSampling ScheduleUnderwood (2020)
Substance (Unit of Measure)Ideal Goal (MCLG)Action Level90th %Sites Above AL/Total SitesViolation90th %Sites Above AL/Total SitesViolationTypical Source
Lead - at consumer taps (ppm)00.0150.00130/10No0.00490/10NoHousehold plumbing
Copper - at consumer taps (ppm) plumbing

Water Hardness

The Carson Water System water is considered soft with readings ranging between 25 and 40 ppm on the hardness scale. Underwood water is considered moderately hard with readings ranging between 60 and 80 ppm.

pH Levels

The pH levels typically range from 6.8 to 7.5 in Carson and 7.3 to 8.0 in Underwood.

Parts Per Million (PPM) Table

Hardness (PPM)
0 to 60Soft
61 to 120 Moderately Hard
121 to 180Hard
180 to upVery Hard
Does My Drinking Water Contain Fluoride?

The Skamania PUD does not add fluoride to the Carson or Underwood drinking water. Some fluoride compounds, such as sodium fluoride and fluorosilicates, dissolve easily into ground water as it moves through gaps and pore spaces between rocks. Most water supplies contain some naturally occurring fluoride. Fluoride can also enter drinking water in discharge from fertilizer or aluminum factories.

Does My Drinking Water Contain Fluoride?

The Skamania PUD does not add fluoride to the Carson or Underwood drinking water. Some fluoride compounds, such as sodium fluoride and fluorosilicates, dissolve easily into ground water as it moves through gaps and pore spaces between rocks. Most water supplies contain some naturally occurring fluoride. Fluoride can also enter drinking water in discharge from fertilizer or aluminum factories.

Why is Sodium Included On The List?

Sodium has been included on the list by EPA to provide an opportunity for more study. While high levels of salt intake may be associated with hypertension in some individuals, sodium levels in drinking water are usually low and unlikely to be a significant contribution to adverse health effects, according to the EPA. The EPA has established a recommended level of 20 parts per million for sodium as a level of concern for those consumers that may be restricted for daily sodium intake in their diets. The EPA is considering updating the guidance level for sodium and says the current one is probably low. FDA imposes quality standards for bottled water that are equivalent to EPA’s drinking water standards so switching to bottled water won’t solve the sodium question if that is a concern for you. Instead, EPA recommends talking with your doctor or a dietitian about reducing sodium in food intake.

Water Use Efficiency

In 2003 the State Legislature passed the Municipal Water Law, which directed the Department of Health (DOH) to adopt a rule that establishes Water Use Efficiency (WUE) requirements for all municipal water suppliers. There were several components in the requirements of the rule. These requirements included auditing for leakage, setting WUE goals, and submitting annual reports to the State DOH.

The Skamania PUD set goals to reduce the average residential water usage by 2% over a 6-year period and reducing the peak day demand by 12 gallons per day (GPD). These goals focus on customer water use and water savings. All users are encouraged to conserve water in their daily lives.

The distribution water mains in Carson and Underwood are aging and leaks are the primary cause of unaccounted use. Although we have made large strides in replacing old waterlines, we still have 11 miles of steel pipe from the 1950s that are scheduled for replacement. We complete ongoing leak detection efforts to help identify underground leaks that are not visible from the surface. The DOH goal for unaccounted water use is 10% or below in Carson and 20% or below in Underwood based on a 3-year rolling average. The current 3-year rolling average for unaccounted use is 30.3% in Carson and 20.8% in Underwood.

Water Quality Table

Disinfectants & Disinfectant By-Products

There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants

EparegulationsCarson Water System (CA)Underwood Water System (UW)
(Unit of Measure)
Ideal Goal (MCL)Highest Level Allowed (MCL)Amount DetectedRangeYear SampledAmount DetectedRangeYear SampledViolationTypical Source
Haloacetic Acids
(HAA5) (ppb)
NA60ND (one sample)NA2022ND (one sample)NA2022NoBy-product of drinking water chlorination
Chlorine (ppm)MRDLG = 4MRDL = 40.62 (average)0.54 to 0.6920220.73 (average)0.49 to 1.22022NoWater additive used to control microbes
TTHMs [Total Trihalomethanes] (ppb)NA806.7 (one sample)NA2022NDNA2022NoBy-product of drinking water disinfection

Inorganic Contaminants

EparegulationsCarson Water System (CA)Underwood Water System (UW)
(Unit of Measure)
Ideal Goal (MCL)Highest Level Allowed (MCL)Amount DetectedRangeYear SampledAmount DetectedRangeYear SampledViolationTypical Source
Arsenic (ppb)010NDNA2022NDNA2020NoErosion of natural deposits; Runoff from orchards
Sodium (ppm)NANA6.9 (one sample)NA20225.6 (one sample)NA2019NoNaturally - occurring
Nitrate (ppm)1010NdNA20221.2 (one average)NA2022NoRunoff from fertilizer use; Leaching from septic tanks, sewage; Erosion of natural deposits
Fluoride (ppm)44NdNA20220.09 (one sample)NA2011NoErosion of natural deposits; Discharge from fertilizer

Microbiological Contaminants

Turbidity is only sampled for surface water sources. 100% of the samples were below the MCL value of 0.3. A value less than 95% constitutes a Treatment Technique (TT) violation. Any measurement in excess of 1 is a violation unless otherwise approved by the state.)

EparegulationsCarson Water System (CA)Underwood Water System (UW)
(Unit of Measure)
Ideal Goal (MCL)Highest Level Allowed (MCL)Amount DetectedRangeYear SampledAmount DetectedRangeYear SampledViolationTypical Source
Turbidity (NTU)NA0.30.030.03 to 0.02022NANANANoSoil runoff
Total Coliform (positive
000NA20220NA2022NoNaturally - occurring
Fecal coliform/E. coli
- in the distribution
system (positive
000NA20220NA2022NoHuman and animal fecal waste

(*A violation occurs when a routine sample and a repeat sample, in any given month, are total coliform positive, and one is also fecal coliform or E. coli positive.)

Radioactive Contaminants

EparegulationsCarson Water System (CA)Underwood Water System (UW)
(Unit of Measure)
Ideal Goal (MCL)Highest Level Allowed (MCL)Amount DetectedRangeYear SampledAmount DetectedRangeYear SampledViolationTypical Source
Gross Alpha (pCi/L)0152.67NA20221.86NA2022NoErosion of natural deposits
Radium 228 (pCi/L)050.783NA20220.773NA2022NoErosion of natural deposits

Customer Feedback Welcome

There are several ways you can get involved in water quality issues:

  • You can communicate with elected officials
  • Participate in public hearings
  • Attend Skamania PUD Commission meetings

The Skamania PUD Board of Commissioners meets at 9 a.m. on the first and third Tuesday of each month (when Tuesday is a holiday, the meeting is held the following day) at Skamania PUD, 1492 Wind River highway in Carson. Board sessions are open to the public. Please check the meeting agenda on our website.

Skamania PUD #1 logoFor more information please contact us at: