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MASON CITY WATER DEPARTMENT

Iowa — Community Water System — PWSID: IA1750048

System Information

PWSIDIA1750048
System NameMASON CITY WATER DEPARTMENT
System TypeCommunity Water System
Water SourceGround Water
Activity StatusActive
Owner TypeLocal
EPA Region07
Serves SchoolNo
WholesalerNo
First ReportedFeb 27, 1979
Last ReportedDec 19, 2025

Location & Contact

StateIowa
CityMASON CITY
ZIP Code50401
AddressATTN DON THORSON WATER SUPT
OrganizationMASON CITY WATER DEPARTMENT
Phone641-421-3683

Population & Service

Population Served27,338
Service Connections19,000

Drinking Water Violations (644)

This water system has 644 violations recorded in the EPA SDWIS database.

Begin Date End Date Contaminant Category Health-Based Major Measured Federal MCL State MCL Status Return to Compliance Rule
Jun 1, 2024 Jun 30, 2024 Revised Total Coliform Rule MON No No — — — Resolved Jun 30, 2024 Revised Total Coliform Rule
Jun 1, 2024 Jun 30, 2024 Revised Total Coliform Rule MON No No — — — Resolved Jun 30, 2024 Revised Total Coliform Rule
Jun 1, 2024 Jun 30, 2024 Revised Total Coliform Rule MON No No — — — Resolved Jun 30, 2024 Revised Total Coliform Rule
Jun 1, 2024 Jun 30, 2024 Revised Total Coliform Rule MON No No — — — Resolved Jun 30, 2024 Revised Total Coliform Rule
Aug 1, 2012 Aug 31, 2012 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Aug 31, 2012 Total Coliform Rule
Aug 1, 2012 Aug 31, 2012 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Aug 31, 2012 Total Coliform Rule
Aug 1, 2012 Aug 31, 2012 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Aug 31, 2012 Total Coliform Rule
Aug 1, 2012 Aug 31, 2012 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Aug 31, 2012 Total Coliform Rule
Aug 1, 2012 Aug 31, 2012 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Aug 31, 2012 Total Coliform Rule
Jul 1, 2009 Aug 31, 2009 Total Haloacetic Acids (HAA5) MR No Yes — 0.060 mg/L — Resolved Aug 31, 2009 Stage 1 Disinfectants and Disinfection Byproducts Rule
Jul 1, 2009 Aug 31, 2009 Total Haloacetic Acids (HAA5) MR No Yes — 0.060 mg/L — Resolved Aug 31, 2009 Stage 1 Disinfectants and Disinfection Byproducts Rule
Jul 1, 2009 Aug 31, 2009 Total Haloacetic Acids (HAA5) MR No Yes — 0.060 mg/L — Resolved Aug 31, 2009 Stage 1 Disinfectants and Disinfection Byproducts Rule
Jul 1, 2009 Aug 31, 2009 Total Haloacetic Acids (HAA5) MR No Yes — 0.060 mg/L — Resolved Aug 31, 2009 Stage 1 Disinfectants and Disinfection Byproducts Rule
Jun 1, 2008 Jun 30, 2008 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Jun 30, 2008 Total Coliform Rule
Jun 1, 2008 Jun 30, 2008 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Jun 30, 2008 Total Coliform Rule
Jun 1, 2008 Jun 30, 2008 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Jun 30, 2008 Total Coliform Rule
Jun 1, 2008 Jun 30, 2008 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Jun 30, 2008 Total Coliform Rule
Jun 1, 2008 Jun 30, 2008 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Jun 30, 2008 Total Coliform Rule
Oct 1, 2004 Dec 31, 2004 Combined Radium (-226 and -228) MCL Yes No 5.2 5 pCi/L — Resolved Dec 31, 2004 Radionuclides and Revised Rad Rule
Oct 1, 2004 Dec 31, 2004 Gross Alpha, Excl. Radon and U MR No Yes — 15 pCi/L — Resolved Dec 31, 2004 Radionuclides and Revised Rad Rule
Oct 1, 2004 Dec 31, 2004 Combined Radium (-226 and -228) MCL Yes No 5.2 5 pCi/L — Resolved Dec 31, 2004 Radionuclides and Revised Rad Rule
Oct 1, 2004 Dec 31, 2004 Combined Radium (-226 and -228) MCL Yes No 5.2 5 pCi/L — Resolved Dec 31, 2004 Radionuclides and Revised Rad Rule
Oct 1, 2004 Dec 31, 2004 Combined Radium (-226 and -228) MCL Yes No 5.2 5 pCi/L — Resolved Dec 31, 2004 Radionuclides and Revised Rad Rule
Oct 1, 2004 Dec 31, 2004 Gross Alpha, Excl. Radon and U MR No Yes — 15 pCi/L — Resolved Dec 31, 2004 Radionuclides and Revised Rad Rule
Oct 1, 2004 Dec 31, 2004 Combined Radium (-226 and -228) MCL Yes No 5.2 5 pCi/L — Resolved Dec 31, 2004 Radionuclides and Revised Rad Rule
Oct 1, 2004 Dec 31, 2004 Gross Alpha, Excl. Radon and U MR No Yes — 15 pCi/L — Resolved Dec 31, 2004 Radionuclides and Revised Rad Rule
Aug 1, 2004 Aug 31, 2004 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Aug 31, 2004 Total Coliform Rule
Aug 1, 2004 Aug 31, 2004 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Aug 31, 2004 Total Coliform Rule
Aug 1, 2004 Aug 31, 2004 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Aug 31, 2004 Total Coliform Rule
Aug 1, 2004 Aug 31, 2004 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Aug 31, 2004 Total Coliform Rule
Jul 1, 2004 Sep 30, 2004 Gross Alpha, Excl. Radon and U MR No Yes — 15 pCi/L — Resolved Sep 30, 2004 Radionuclides and Revised Rad Rule
Jul 1, 2004 Sep 30, 2004 Gross Alpha, Excl. Radon and U MR No Yes — 15 pCi/L — Resolved Sep 30, 2004 Radionuclides and Revised Rad Rule
Jul 1, 2004 — Consumer Confidence Rule Other No No — — — Resolved Jun 28, 2006 Consumer Confidence Rule
Jul 1, 2004 Sep 30, 2004 Combined Radium (-226 and -228) MCL Yes No 5.7 5 pCi/L — Resolved Sep 30, 2004 Radionuclides and Revised Rad Rule
Jul 1, 2004 Sep 30, 2004 Combined Radium (-226 and -228) MCL Yes No 5.7 5 pCi/L — Resolved Sep 30, 2004 Radionuclides and Revised Rad Rule
Jul 1, 2004 Sep 30, 2004 Combined Radium (-226 and -228) MCL Yes No 5.7 5 pCi/L — Resolved Sep 30, 2004 Radionuclides and Revised Rad Rule
Jul 1, 2004 — Consumer Confidence Rule Other No No — — — Resolved Jun 28, 2006 Consumer Confidence Rule
Jul 1, 2004 — Consumer Confidence Rule Other No No — — — Resolved Jun 28, 2006 Consumer Confidence Rule
Jul 1, 2004 Sep 30, 2004 Combined Radium (-226 and -228) MCL Yes No 5.7 5 pCi/L — Resolved Sep 30, 2004 Radionuclides and Revised Rad Rule
Jul 1, 2004 Sep 30, 2004 Gross Alpha, Excl. Radon and U MR No Yes — 15 pCi/L — Resolved Sep 30, 2004 Radionuclides and Revised Rad Rule
Jul 1, 2004 Sep 30, 2004 Combined Radium (-226 and -228) MCL Yes No 5.7 5 pCi/L — Resolved Sep 30, 2004 Radionuclides and Revised Rad Rule
Jul 1, 2004 — Consumer Confidence Rule Other No No — — — Resolved Jun 28, 2006 Consumer Confidence Rule
Mar 1, 2004 Mar 31, 2004 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Mar 31, 2004 Total Coliform Rule
Mar 1, 2004 Mar 31, 2004 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Mar 31, 2004 Total Coliform Rule
Mar 1, 2004 Mar 31, 2004 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Mar 31, 2004 Total Coliform Rule
Mar 1, 2004 Mar 31, 2004 Coliform (TCR) MCL Yes No — 5% of samples — Resolved Mar 31, 2004 Total Coliform Rule
Jan 1, 2004 Mar 31, 2004 Combined Radium (-226 and -228) MCL Yes No 8.2 5 pCi/L — Resolved Mar 31, 2004 Radionuclides and Revised Rad Rule
Jan 1, 2004 Mar 31, 2004 Combined Radium (-226 and -228) MCL Yes No 8.2 5 pCi/L — Resolved Mar 31, 2004 Radionuclides and Revised Rad Rule
Jan 1, 2004 Mar 31, 2004 Combined Radium (-226 and -228) MCL Yes No 8.2 5 pCi/L — Resolved Mar 31, 2004 Radionuclides and Revised Rad Rule
Jan 1, 2004 Mar 31, 2004 Combined Radium (-226 and -228) MCL Yes No 8.2 5 pCi/L — Resolved Mar 31, 2004 Radionuclides and Revised Rad Rule

About This Water System

Public water system data comes from the EPA Safe Drinking Water Information System (SDWIS). Systems with violations must notify customers. Contact your water utility for the latest annual water quality report.

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