To mitigate the Imminent and Substantial Endangerment at the Warm Springs Public Water System
(System), ECAD plans to issue a 1431 Order. This 1431 Order will require: 1) provision of an
alternative water supply, 2) monthly assessment and reporting to EPA of priority actions for the coming
months, and 3) establishing a priority schedule that requires upgrades, purchases, and fixes to
equipment and work practices to address the recent pattern of high turbidity and lack of adequate
residual chlorine in the distribution system, both of which pose an Imminent and Substantial
Engagement to the System's 3,800 customers. The System has issued boil water notices due to a lack of
coagulant and/or other factors resulting in high and extremely high turbidity three times in the last six
months, including twice in the last three weeks. The emergency administrative order would remain
open until root causes of these issues are addressed and that work will be overseen by EPA through a
workgroup consisting of EPA, the Tribe, and other relevant parties such as IHS. The 1431 SDWA
Order will require the Tribe to provide alternate water when EPA determines such action is warranted
and monitoring shows there is an issue (e.g., future turbidity exceedances or failure to maintain
microbial treatment).