EPA and Respondents San Carlos Apache Tribe and San Carlos Apache Tribal Utility Authority voluntarily enter into this Amended Administrative Order ( Order ) on Consent for the purpose of bringing nine San Carlos Apache Tribe public water systems, which service over 14,900 residents, owned and operated by the Respondents into compliance with the requirements of the federal Safe Drinking Water Act (SDW) and its National Primary Drinking Water Regulations. This Order amends and supersedes the Administrative Order on Consent originally entered into between EPA and Respondents in October 2011 (EPA Docket Number PWS-AOC-20 12-6000).