The U.S. Environmental Protection Agency (EPA or The Agency) is required by the Safe Drinking Water Act (SDWA), as amended in 1996, to publish a list of contaminants (Drinking Water Contaminant Candidate List, or CCL) that are known or anticipated to occur in public water systems, and which may require regulation under the SDWA. The CCL 2 was published in a Federal Register Notice (FR Notice) on February 24, 2005 (70 FR 9071). The Agency is also required to make Regulatory Determinations on at least five of the CCL contaminants following publication. EPA published preliminary regulatory determinations for 11 of 51 total contaminants from CCL 2 on May 1, 2007 (72 FR 24016). In the 2007 notice, perchlorate was not part of the list of 11 contaminants, however, the Agency asked for new information and data related to perchlorate. Subsequently, EPA made a final regulatory determination not to regulate the 11 of the contaminants identified in the May 1, 2007 Federal Register notice. Responses to public comment regarding these 11 contaminants were answered as part of the final regulatory determination process and posted to www.regulations.gov (refer to document ID EPA-HQ-OW-2007-0068-0178). The Agency deferred responding to comments on perchlorate, and issued a separate preliminary determination not to regulate perchlorate on October 17, 2008 (73 FR 66895), followed by an additional public comment period.