ANGWIN, CA · Napa County

HOWELL MOUNTAIN MUTUAL WATER COMPANY Water System

Current status

No open violations on record as of July 4, 2026.

This system's next federally required Consumer Confidence Report is due July 1, 2027, under the EPA's revised reporting rule.

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 California’s official records. Always confirm current status with California before making decisions based on this information.

System facts

System ID (PWSID): CA2810001
System type: Community Water System
Population served: 1,240
Service connections: 379
Ownership: privately owned
Water source: surface water (rivers, lakes, or reservoirs)

Violation history

Maximum Contaminant Level Violation, Average
Health-based
TTHM
January 1, 2011 – March 31, 2011
Resolved
Maximum Contaminant Level Violation, Average
Health-based
Total Haloacetic Acids (HAA5)
January 1, 2011 – March 31, 2011
Resolved
Maximum Contaminant Level Violation, Average
Health-based
Total Haloacetic Acids (HAA5)
October 1, 2010 – December 31, 2010
Resolved
Maximum Contaminant Level Violation, Average
Health-based
Total Haloacetic Acids (HAA5)
July 1, 2010 – September 30, 2010
Resolved
Maximum Contaminant Level Violation, Average
Health-based
TTHM
January 1, 2010 – March 31, 2010
Resolved
Maximum Contaminant Level Violation, Average
Health-based
TTHM
October 1, 2009 – December 31, 2009
Resolved
Monitoring and Reporting (DBP)
—
Total Haloacetic Acids (HAA5)
July 1, 2009 – September 30, 2009
Resolved
Maximum Contaminant Level Violation, Average
Health-based
TTHM
July 1, 2009 – September 30, 2009
Resolved
Maximum Contaminant Level Violation, Average
Health-based
Total Haloacetic Acids (HAA5)
July 1, 2009 – September 30, 2009
Resolved
Monitoring and Reporting (DBP)
—
TTHM
July 1, 2009 – September 30, 2009
Resolved
Maximum Contaminant Level Violation, Average
Health-based
TTHM
April 1, 2009 – June 30, 2009
Resolved
Maximum Contaminant Level Violation, Average
Health-based
Total Haloacetic Acids (HAA5)
April 1, 2009 – June 30, 2009
Resolved
Maximum Contaminant Level Violation, Average
Health-based
Total Haloacetic Acids (HAA5)
October 1, 2008 – December 31, 2008
Resolved
Monitoring and Reporting (DBP)
—
Total Haloacetic Acids (HAA5)
July 1, 2008 – September 30, 2008
Resolved
Maximum Contaminant Level Violation, Average
Health-based
TTHM
July 1, 2008 – September 30, 2008
Resolved
Maximum Contaminant Level Violation, Average
Health-based
Total Haloacetic Acids (HAA5)
July 1, 2008 – September 30, 2008
Resolved
Maximum Contaminant Level Violation, Average
Health-based
Total Haloacetic Acids (HAA5)
October 1, 2005 – December 31, 2005
Resolved
Notification, Public
—
No contaminant on record
August 1, 1987 – August 31, 1987
Archived

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

Period	Violation	Contaminant / rule	Health-based	Status
January 1, 2011 – March 31, 2011	Maximum Contaminant Level Violation, Average	TTHM	Health-based	Resolved
January 1, 2011 – March 31, 2011	Maximum Contaminant Level Violation, Average	Total Haloacetic Acids (HAA5)	Health-based	Resolved
October 1, 2010 – December 31, 2010	Maximum Contaminant Level Violation, Average	Total Haloacetic Acids (HAA5)	Health-based	Resolved
July 1, 2010 – September 30, 2010	Maximum Contaminant Level Violation, Average	Total Haloacetic Acids (HAA5)	Health-based	Resolved
January 1, 2010 – March 31, 2010	Maximum Contaminant Level Violation, Average	TTHM	Health-based	Resolved
October 1, 2009 – December 31, 2009	Maximum Contaminant Level Violation, Average	TTHM	Health-based	Resolved
July 1, 2009 – September 30, 2009	Monitoring and Reporting (DBP)	Total Haloacetic Acids (HAA5)	—	Resolved
July 1, 2009 – September 30, 2009	Maximum Contaminant Level Violation, Average	TTHM	Health-based	Resolved
July 1, 2009 – September 30, 2009	Maximum Contaminant Level Violation, Average	Total Haloacetic Acids (HAA5)	Health-based	Resolved
July 1, 2009 – September 30, 2009	Monitoring and Reporting (DBP)	TTHM	—	Resolved
April 1, 2009 – June 30, 2009	Maximum Contaminant Level Violation, Average	TTHM	Health-based	Resolved
April 1, 2009 – June 30, 2009	Maximum Contaminant Level Violation, Average	Total Haloacetic Acids (HAA5)	Health-based	Resolved
October 1, 2008 – December 31, 2008	Maximum Contaminant Level Violation, Average	Total Haloacetic Acids (HAA5)	Health-based	Resolved
July 1, 2008 – September 30, 2008	Monitoring and Reporting (DBP)	Total Haloacetic Acids (HAA5)	—	Resolved
July 1, 2008 – September 30, 2008	Maximum Contaminant Level Violation, Average	TTHM	Health-based	Resolved
July 1, 2008 – September 30, 2008	Maximum Contaminant Level Violation, Average	Total Haloacetic Acids (HAA5)	Health-based	Resolved
October 1, 2005 – December 31, 2005	Maximum Contaminant Level Violation, Average	Total Haloacetic Acids (HAA5)	Health-based	Resolved
August 1, 1987 – August 31, 1987	Notification, Public	—	—	Archived

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

Enforcement actions

December 31, 2023State Compliance achieved2 linked violations
September 30, 2021State Compliance achieved1 linked violation
March 11, 2018State Compliance achieved5 linked violations
August 25, 1993State Administrative/Compliance Order without penalty issued4 linked violations

Contact

HIERS, TANNER

707-965-2205

ANGWIN, CA 94508