On October 4, 2017, the Crow Nation reported vandalism to their water treatment plant in Crow Agency, Montana (population ~1800). Three chemical storage tanks were damaged during the incident. In addition, the facility's clarifier tank, clear well, plumbing, control system, chlorine distribution system and backwash lagoon were all impacted.
Less than 20 pounds of dry filter agent containing poly acrylamide was dumped directly into the clear well and an unknown amount of contaminated water may have entered the public water supply before operators were able to take the treatment plant off-line, so the EPA instructed the public to not drink nor come into contact with the water in their taps.
Sample results collected from the drinking water system, and plant operators opened hydrants in the community on the main distribution lines to flush remnant contaminants. The water restrictions were lifted and the community was encouraged to let their taps run before using the water. Residual chlorine levels in the system were monitored closely during this process to insure bacteria did not form while the system was restricted.
EPA's Drinking Water Program and the Tribe facilitated all remaining steps that were required to bring the plant back on-line including all required sampling and inspection activities. The treatment plant is operational.