YELLOWTAIL, MT · Big Horn County

YELLOWTAIL DAM MK UPPER SYSTEM Water System

Inactive system

This water system is marked inactive in EPA’s federal records as of November 17, 2022. It is no longer an operating public water system under this PWSID, and no compliance deadlines — including the 2027 Consumer Confidence Report rule — apply to it.

If you are a resident looking for your current water provider, see water systems in Big Horn County, MT.

Data sourced from the EPA ECHO database (SDWA bulk download), last refreshed July 4, 2026. This is a record-keeping and public-information tool — it does not replace Montana’s official records. Always confirm current status with Montana before making decisions based on this information.

System facts

System ID (PWSID): MT0002531
System type: Community Water System
Population served: 40
Service connections: 12
Ownership: federal government
Water source: groundwater (wells)

Violation history

Monitoring, Regular
—
Asbestos
January 1, 2011 – December 31, 2013
Archived
Monitoring, Regular
—
Nitrate-Nitrite
January 1, 2003 – December 31, 2003
Resolved
Consumer Confidence Report Complete Failure to Report
—
Consumer Confidence Rule
July 1, 2002 – October 2, 2003
Resolved
Monitoring, Regular
—
Trichloroethylene
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
HEXACHLOROBENZENE
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
1,1-Dichloroethylene
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
1,1,1-Trichloroethane
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
LASSO
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Heptachlor
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Heptachlor epoxide
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
2,4,5-TP
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
p-Dichlorobenzene
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Arsenic
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Chromium
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Fluoride
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Mercury
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Nickel
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Antimony, Total
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Thallium, Total
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
BHC-GAMMA
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Methoxychlor
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Toxaphene
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Dalapon
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Di(2-ethylhexyl) adipate
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Di(2-ethylhexyl) phthalate
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Aldicarb sulfoxide
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Aldicarb
January 1, 2002 – December 31, 2004
Resolved
Monitoring, Regular
—
Atrazine
January 1, 2002 – December 31, 2004
Resolved
Consumer Confidence Report Complete Failure to Report
—
Consumer Confidence Rule
July 1, 2000 – August 19, 2004
Resolved
Monitoring, Routine Major (TCR)
—
Coliform (TCR)
September 1, 1997 – September 30, 1997
Resolved
Monitoring, Routine Major (TCR)
—
Coliform (TCR)
April 1, 1997 – April 30, 1997
Resolved
Monitoring, Routine Major (TCR)
—
Coliform (TCR)
April 1, 1995 – April 30, 1995
Resolved
Monitoring, Regular
—
Mercury
June 24, 1981 – July 23, 1981
Archived

Archived closed in EPA's records (typically due to age or a data correction)Resolved addressed and confirmed by the state

Period	Violation	Contaminant / rule	Health-based	Status
January 1, 2011 – December 31, 2013	Monitoring, Regular	Asbestos	—	Archived
January 1, 2003 – December 31, 2003	Monitoring, Regular	Nitrate-Nitrite	—	Resolved
July 1, 2002 – October 2, 2003	Consumer Confidence Report Complete Failure to Report	Consumer Confidence Rule	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Trichloroethylene	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	HEXACHLOROBENZENE	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	1,1-Dichloroethylene	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	1,1,1-Trichloroethane	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	LASSO	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Heptachlor	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Heptachlor epoxide	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	2,4,5-TP	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	p-Dichlorobenzene	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Arsenic	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Chromium	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Fluoride	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Mercury	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Nickel	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Antimony, Total	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Thallium, Total	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	BHC-GAMMA	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Methoxychlor	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Toxaphene	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Dalapon	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Di(2-ethylhexyl) adipate	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Di(2-ethylhexyl) phthalate	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Aldicarb sulfoxide	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Aldicarb	—	Resolved
January 1, 2002 – December 31, 2004	Monitoring, Regular	Atrazine	—	Resolved
July 1, 2000 – August 19, 2004	Consumer Confidence Report Complete Failure to Report	Consumer Confidence Rule	—	Resolved
September 1, 1997 – September 30, 1997	Monitoring, Routine Major (TCR)	Coliform (TCR)	—	Resolved
April 1, 1997 – April 30, 1997	Monitoring, Routine Major (TCR)	Coliform (TCR)	—	Resolved
April 1, 1995 – April 30, 1995	Monitoring, Routine Major (TCR)	Coliform (TCR)	—	Resolved
June 24, 1981 – July 23, 1981	Monitoring, Regular	Mercury	—	Archived

Archived closed in EPA's records (typically due to age or a data correction)Resolved addressed and confirmed by the state

Enforcement actions

February 6, 2018State Public Notification received1 linked violation
January 25, 2018State Compliance achieved1 linked violation
January 23, 2018State Violation/Reminder Notice1 linked violation
January 23, 2018State Public Notification requested1 linked violation
February 16, 2016State Compliance achieved1 linked violation
February 1, 2016State Compliance achieved1 linked violation
February 1, 2016State Violation/Reminder Notice1 linked violation
February 10, 2014State Public Notification received1 linked violation
January 24, 2014State Public Notification requested1 linked violation
January 24, 2014State Violation/Reminder Notice1 linked violation
January 15, 2014State Compliance achieved1 linked violation
January 15, 2014State Public Notification requested1 linked violation
January 15, 2014State Violation/Reminder Notice1 linked violation
July 20, 2012State Compliance achieved1 linked violation
January 14, 2011State Violation/Reminder Notice1 linked violation
May 15, 2009State Compliance achieved1 linked violation
May 15, 2009State Compliance achieved1 linked violation
May 15, 2009State Compliance achieved1 linked violation
May 15, 2009State Compliance achieved1 linked violation
August 5, 2008State Violation/Reminder Notice1 linked violation
August 5, 2008State Public Notification requested1 linked violation
July 31, 2008State Compliance achieved1 linked violation
January 18, 2007State Compliance achieved1 linked violation
January 14, 2007State Public Notification requested1 linked violation
January 14, 2007State Violation/Reminder Notice1 linked violation
February 14, 2006State Compliance achieved1 linked violation
December 25, 2005State Violation/Reminder Notice1 linked violation
November 22, 2005State Compliance achieved1 linked violation
September 27, 2005State Public Notification requested4 linked violations
June 7, 2005State Compliance achieved14 linked violations
April 15, 2005State Public Notification requested22 linked violations
August 19, 2004State Compliance achieved1 linked violation
May 12, 2004State Public Notification requested1 linked violation
May 12, 2004State Violation/Reminder Notice1 linked violation
December 23, 2002State Violation/Reminder Notice1 linked violation

Last known contact on file (system is inactive)

BYRNES, MICHAEL

406-666-3201

YELLOWTAIL, MT 59035