The Great Perchlorate Debate: No Federal Action…For Now

After over 20 years of debate and the impending requirement for federal regulation, the United States Environmental Protection Agency (EPA) has made a final determination to not develop a federal action level for perchlorate in drinking water.  

What is perchlorate?

Perchlorate is a chemical compound (CIO4-) that is naturally occurring and can also be man-made.  Perchlorate is comprised of a chlorine atom surrounded by four oxygen atoms and acts mostly as a salt that accumulates slightly below the soil surface, particularly in dry desert areas.  The compounds including sodium perchlorate, potassium perchlorate, and ammonia perchlorate form perchloric acid.  Perchloric acid has been used since the early 1900s in rocket fuel.  Perchlorate is also found as a natural impurity in nitrate salts used to produce fertilizers.  Perchlorate is commonly used for flares, matches, explosives, and even in fireworks.  Possible negative health effects of perchlorate were first reported by scientists in 1929, when a connection was drawn to the compound reducing the uptake of iodide into the thyroid gland, resulting in metabolic effects and potential birth defects. 

A little background

EPA started measuring perchlorate as far back as the 1980s when it was discovered at Superfund sites in California.  Over the years, EPA and multiple other regulatory, private, research, and industry groups conducted studies, resulting in varying recommendations for appropriate action levels.  Groups such as the Inter-Agency Perchlorate Steering Committee and Perchlorate Study Group (PSG) were formed to review studies and research the need for action levels.  The EPA provided interim and advisory guidelines, but most were heavily debated, as parties felt the levels were over- or under-protective of human health. 

In a step towards an enforceable standard, in February 2011, the EPA issued a “Proposed Rule” for the regulation of perchlorate in accordance with the criteria of the Safe Drinking Water Act (SDWA) so that a Maximum Contaminant Level Goal (MCLG) could be established.  In short, the EPA was starting the process to develop a national primary drinking water regulation (NPDWR). 

Five years later, on February 19, 2016, the National Resource Defense Council (NRDC) filed a complaint in the United States District Court for the Southern District of New York against the EPA, stating that EPA had failed to meet the statutory deadlines under the SDWA by not yet issuing a draft action level.  The complaint resulted in a Consent Decree requiring the EPA to establish a final MCLG and NPDWR for perchlorate by December 19, 2019. 

On October 1, 2019, EPA and NRDC agreed to an extension of 6 months to June 19, 2020.  Then, on June 18, 2020, the EPA issued a press release stating that based on the best available science and information, perchlorate “does not meet the criteria for regulation as a drinking water contaminant under SDWA.  Therefore, the agency is withdrawing the 2011 regulatory determination and is making a final determination to not issue a national regulation for perchlorate at this time.”

Should I continue monitoring for perchlorate?

Future monitoring largely depends on your state’s standards.  Many states had previously decided that, instead of waiting for a federal promulgated standard, they would issue their own action levels for drinking water.  Today, at least 19 states have their own action levels for perchlorate ranging from as low as 0.8 ug/L in Maine to as high as 71 ug/L (non-residential) in Kansas. 

  • For states where action levels exist, and sites being managed under that state's environmental orders, perchlorate may need to be monitored. These states include: Alabama, California, Colorado, Florida, Illinois, Indiana, Kansas, Maine, Maryland, Nebraska, Nevada, New Mexico, Pennsylvania, Texas, Utah, Vermont, Virginia, West Virginia, and Wyoming.
  • On sites managed in states other than those listed above, there may be an opportunity to discuss removing perchlorate from the target analyte list.

If you have questions regarding monitoring perchlorate, please contact us. 

Christina Hiegel, PE
Senior Engineer
[email protected]

Did you find this information useful? Click the icons below to share on your social channels.

facebook twitter linkedin
Other News


Receive the latest technical and regulatory updates in your inbox.