Harmful Algal Bloom Advisory

Triadelphia Reservoir

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WSSC Water is participating in the U.S. Environmental Protection Agency’s (EPA) fourth round of the Unregulated Contaminant Monitoring Rule (UCMR4).  Approximately 6,000 utilities nationwide will monitor unregulated contaminants for a year to help the EPA determine the occurrence of these contaminants in drinking water and whether or not they need to be regulated for protection of public health. More information on UCMR4 is available here.

As part of the UCMR4 program, WSSC Water is collecting two sets of samples quarterly throughout 2018. Samples will be collected from our source and finished water from both of our water treatment plants as well as sixteen distribution system sites representing the WSSC Water distribution system. In addition to quarterly samples, cyanotoxin samples will be collected twice a month beginning in July 2018 and ending in October 2018. The detected contaminants of the UCMR4 sampling are listed in this 2022 Q1 UCMR Bicounty Table

We are committed to protecting public health and will continue to monitor and support EPA’s research on these contaminants.

*Parts Per Billion (ppb) = Half of a teaspoon of water in an Olympic-sized swimming pool would be about one part per billion. Also, the equivalent of one minute in 2,000 years, or one penny in $10 million.

Review the latest Detected UCMR4 Contaminants Quarter 1 2022


MCL – Maximum Contaminant Level –  “The maximum permissible level of a contaminant in water which is delivered to any user of a public water system."(EPA)
MCLG – Maximum Contaminant Level Goal – “The level of a contaminant in drinking water below which there is no known or expected risk to health.” (EPA)

Last Modified: July 20, 2022, 10:13 am EDT