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Explanation of Terms

Abbreviations/Explanation of Terms


AL – Action Level

The concentration of a contaminant which, if exceeded, triggers treatment or other requirements which a water system must follow.

CFU - Colony Forming Units

A measurement used to count the number of bacteria colonies found in water.

EPA-Environmental Protection Agency

LRAA-Locational Running Annual Average
The average of 4 consecutive quarterly results at each monitored sample location.  The LRAA should not exceed 80 ug/L for TTHM and 60 ug/L for HAA5

MCL - Maximum Contaminant Level
The highest level of contaminant that is allowed in drinking water. MCLs are set as close to the MCLGs as feasible using the best available treatment technology.

MCLG – Maximum Contaminant Level Goal
The level of contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety.

N/A – Not applicable

N/D – Not detected

NTU - Nephelometric Turbidity Units
A measure of suspended particles in water. High quality water has a low NTU.

ppb - parts per billion or micrograms per liter (ug/L)
One part per billion corresponds to approximately 1 second in 31.7 years.

ppm - parts per million or milligrams per liter (mg/L)
One part per million corresponds to 1 second in 11.5 years.

ppt – parts per trillion or nanogram per liter (ng/L)
One part per million corresponds to 1 second in 32,000 years.

pCi/L – picocuries per liter
A measurement of radioactivity

SMCL-Secondary Maximum Contaminant Level
Non-mandatory water quality standards for contaminants. EPA does not enforce these "secondary maximum contaminant levels" or "SMCLs." They are established only as guidelines to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color and odor. These contaminants are not considered to present a risk to human health at the SMCL.

TT – treatment technique
A required process intended to reduce the level of a contaminant

< - less than

90th Percentile
Represents the highest value found out of 90 percent of the samples taken in a representative group.  If the 90th percentile is greater than the action level, it will trigger a treatment or other requirements that a water system must follow

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