Clean Water Current

(February 19, 2020) – EPA released its Draft Technical Support Document for Implementing the 2019 Recommended Human Health Recreational Ambient Water Quality Criteria or Swimming Advisories for Microcystins and Cylindrospermopsin on December 16, 2019. This guidance document was EPA’s effort to help state regulatory authorities that choose to adopt the Agency’s recommended cyanotoxin values with implementing the criteria or swimming advisories.  

NACWA submitted comments on the document which highlight concerns with EPA’s guidance for implementation. Specifically, NACWA urges EPA to develop a standardized analytical methodology that meets the data quality objectives in 40 CFR Part 136 so that regulated entities have reassurance their analytical results will determine their compliance status. EPA makes clear that “analytical results may vary depending on the analytical methods used” and that “the presence of cyanobacteria does not necessarily mean that cyanotoxins are being produced.” NACWA also requests EPA require states to use toxin concentration rather than cyanobacterial cell density as the basis for determining whether there has been any exceedance in water quality compliance. 

NACWA submitted comments in March 2017 urging EPA in its request for scientific views not to issue ambient water quality criteria for microcystins and cylindrospermopsin because of the inherent challenges associated with mitigating harmful algal bloom formation and cyanotoxin production for Clean Water Act permittees, including publicly owned treatment works (POTWs) that typically do not discharge cyanotoxins. Rather, NACWA advocated that swimming advisory programs would offer the greatest public health protections. 

If members have questions on this Draft Technical Support Document for cyanotoxins, please contact Emily Remmel, NACWA’s Director of Regulatory Affairs.