Long Term 2 Enhanced Surface Water Treatment Rule

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The Long Term 2 Enhanced Surface Water Treatment Rule ("LT2ESWTR" or simply "LT2") is a 2006 regulation promulgated by the United States Environmental Protection Agency (EPA) pursuant to the Safe Drinking Water Act. The rule required public water systems to install more stringent treatment systems to control the microorganism cryptosporidium and other pathogens.[1]

Historical context[edit]

Drafting of the LT2 rule began following the 1993 Milwaukee Cryptosporidiosis outbreak, in which it is believed that municipal sewage infected with cryptosporidium was accidentally discharged into the city of Milwaukee, Wisconsin's drinking water.[2]


The LT2 rule has been criticized for mandating costly public works projects (such as coverage of open-air reservoirs) that may be unnecessary[3] and/or unlikely to address the kind of problem that was responsible for the Milwaukee incident; as stated by William R. MacKenzie, M.D., a Centers for Disease Control epidemiologist who served as the Epidemic Intelligence Officer on the Milwaukee case, "Standards for water treatment facilities were about to be implemented throughout the nation; but even those would not have stopped the Milwaukee outbreak."[2]

Critics have alleged that LT2's mandates may have been aimed more at appeasing the corporate public-works-engineering industry, which lobbied EPA during the LT2 drafting process, and which has benefited from hundreds of millions of dollars in ensuing public works contracts.[4][5]

Review of regulatory requirements[edit]

In response to growing criticism that the rule unfairly burdens public water systems that are not exposed to municipal sewage, EPA Administrator Lisa Jackson announced on August 19, 2011, that the agency would reconsider the scientific validity of LT2's reservoir coverage and treatment requirements during its "Periodic Retrospective Review of Regulations" in 2016.[6]

EPA conducted three public meetings in 2011 and 2012 about the LT2 rule, and invited the public to submit information and data to support future regulatory decisions. In a 2017 Federal Register notice, EPA stated that it "did not identify new information related to potentially revising" the regulatory requirements for cryptosporidium and other listed pathogens, and requested additional public comments.[7]


  1. ^ United States Environmental Protection Agency (EPA)(2006-01-05). "National Primary Drinking Water Regulations: Long Term 2 Enhanced Surface Water Treatment Rule." Federal Register, 71 FR 654
  2. ^ a b MacKenzie, William R. (September 2007). "Cryptosporidium in Milwaukee's water supply caused widespread illness". Healio. Thorofare, NJ: Slack Inc. Retrieved 2013-08-16.
  3. ^ "Federal government may scrap much-derided $1.6 billion reservoir cap". NY Daily News. 2011-08-21. Retrieved 2013-08-16.
  4. ^ "News Continued". Slo Coast Journal. Retrieved 2013-08-16.
  5. ^ "Who Is Joe Glicker? | Would you like a nice cup of Radon?". Whoisjoeglicker.wordpress.com. Retrieved 2013-08-16.
  6. ^ "EPA letter to Senator Charles Schumer" (PDF). Opb.org. 2011-08-19.
  7. ^ EPA (2017-01-11). "National Primary Drinking Water Regulations; Announcement of the Results of EPA's Review of Existing Drinking Water Standards and Request for Public Comment and/or Information on Related Issues." 82 FR 3539