EPA Releases Fourth Set of UCMR 4 Results
On July 19, 2019, EPA posted the fourth set of analytical results and a Data Summary for the fourth Unregulated Contaminant Monitoring Rule, or UCMR 4. Under the rule, all large public water 
systems (PWSs) and a representative subset of small PWSs are required to monitor for up to 30 contaminants between 2018 and 2020. In UCMR 4, these contaminants include: metals, cyanotoxins, pesticides, brominated disinfection byproducts, alcohols, and semi-volatile organic chemicals. The summary document includes a national summary of the data received as of July 1, 2019. EPA will update the information on UCMR’s occurrence webpage quarterly. The data are subject to change until a final dataset is published in early 2022.
