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New UCMR Data Released

EPA has released another batch of test results from the current round of Unregulated Contaminant Monitoring Rule (UCMR) monitoring.  A convenient summary report is available online but the full set of data collected so far can also be downloaded.  Monitoring for this fourth UCMR began in 2018 and runs until 2020.  EPA releases data approximately quarterly once the water systems and laboratories have reported and verified their data.

Of the 30 contaminants being monitored in this round, a few have yet to be detected, which is typical of every UCMR.  As expected, a few have been detected in a significant number of systems, including naturally occurring manganese and disinfection byproduct Haloacetic Acids (HAA).  Very few have levels above a health-based reference concentration, although there are some, and these may require a response by local water systems and state programs.  The percentage of public water systems with at least one value over the reference concentration is 7.4% for HAA5 (79 PWS), 2.4% for quinoline (25 PWS), 1.6% for manganese (19 PWS), 0.5% for total microcystins (4 PWS), and 0.2% for alpha-hexachlorocyclohexane (2 PWS).  A few other contaminants do not have reference concentrations but were found frequently enough to generate some local interest, including germanium (145 PWS), anatoxin-a (14 PWS), and o-toluidine (10 PWS).