LYON-SIOUX RWS-BIG SIOUX
Iowa — Community Water System — PWSID: IA6000755
System Information
| PWSID | IA6000755 |
| System Name | LYON-SIOUX RWS-BIG SIOUX |
| System Type | Community Water System |
| Water Source | Ground Water |
| Activity Status | Active |
| Owner Type | Private |
| EPA Region | 07 |
| Serves School | No |
| Wholesaler | No |
| First Reported | Feb 27, 1979 |
| Last Reported | Dec 19, 2025 |
Location & Contact
| State | Iowa |
| City | ROCK RAPIDS |
| ZIP Code | 51246 |
| Address | ATTN DAVE HARMSEN |
| Organization | LYON-SIOUX RURAL WATER SYSTEM |
| Phone | 712-472-3755 |
Population & Service
| Population Served | 1,530 |
| Service Connections | 612 |
Drinking Water Violations (69)
This water system has 69 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Oct 1, 2019 | Sep 30, 2020 | Nitrite | MR | No | Yes | — | 1 mg/L | — | Resolved | Sep 30, 2020 | Nitrate Rule |
| Oct 1, 2019 | Sep 30, 2020 | Nitrite | MR | No | Yes | — | 1 mg/L | — | Resolved | Sep 30, 2020 | Nitrate Rule |
| Oct 1, 2019 | Sep 30, 2020 | Nitrite | MR | No | Yes | — | 1 mg/L | — | Resolved | Sep 30, 2020 | Nitrate Rule |
| Oct 1, 2019 | Sep 30, 2020 | Nitrite | MR | No | Yes | — | 1 mg/L | — | Resolved | Sep 30, 2020 | Nitrate Rule |
| Jul 1, 2012 | Jun 30, 2021 | Combined Radium (-226 and -228) | MR | No | Yes | — | 5 pCi/L | — | Resolved | Jun 30, 2021 | Radionuclides and Revised Rad Rule |
| Jul 1, 2012 | Jun 30, 2021 | Combined Radium (-226 and -228) | MR | No | Yes | — | 5 pCi/L | — | Resolved | Jun 30, 2021 | Radionuclides and Revised Rad Rule |
| Jul 1, 2012 | Jun 30, 2021 | Combined Radium (-226 and -228) | MR | No | Yes | — | 5 pCi/L | — | Resolved | Jun 30, 2021 | Radionuclides and Revised Rad Rule |
| Jul 1, 2012 | Jun 30, 2021 | Combined Radium (-226 and -228) | MR | No | Yes | — | 5 pCi/L | — | Resolved | Jun 30, 2021 | Radionuclides and Revised Rad Rule |
| Jul 1, 2010 | Sep 30, 2010 | Nitrate | MR | No | Yes | — | 10 mg/L | — | Resolved | Sep 30, 2010 | Nitrate Rule |
| Jul 1, 2010 | Sep 30, 2010 | Nitrate | MR | No | Yes | — | 10 mg/L | — | Resolved | Sep 30, 2010 | Nitrate Rule |
| Jul 1, 2010 | Sep 30, 2010 | Nitrate | MR | No | Yes | — | 10 mg/L | — | Resolved | Sep 30, 2010 | Nitrate Rule |
| Jul 1, 2010 | Sep 30, 2010 | Nitrate | MR | No | Yes | — | 10 mg/L | — | Resolved | Sep 30, 2010 | Nitrate Rule |
| Jan 1, 2005 | Dec 31, 2013 | Mercury | MR | No | Yes | — | 0.002 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Mercury | MR | No | Yes | — | 0.002 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Mercury | MR | No | Yes | — | 0.002 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Mercury | MR | No | Yes | — | 0.002 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Selenium | MR | No | Yes | — | 0.05 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Selenium | MR | No | Yes | — | 0.05 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Selenium | MR | No | Yes | — | 0.05 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Selenium | MR | No | Yes | — | 0.05 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Thallium, Total | MR | No | Yes | — | 0.002 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Thallium, Total | MR | No | Yes | — | 0.002 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Thallium, Total | MR | No | Yes | — | 0.002 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Thallium, Total | MR | No | Yes | — | 0.002 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Arsenic | MR | No | Yes | — | 0.010 mg/L | — | Resolved | Dec 31, 2013 | Arsenic Rule |
| Jan 1, 2005 | Dec 31, 2013 | Arsenic | MR | No | Yes | — | 0.010 mg/L | — | Resolved | Dec 31, 2013 | Arsenic Rule |
| Jan 1, 2005 | Dec 31, 2013 | Arsenic | MR | No | Yes | — | 0.010 mg/L | — | Resolved | Dec 31, 2013 | Arsenic Rule |
| Jan 1, 2005 | Dec 31, 2013 | Arsenic | MR | No | Yes | — | 0.010 mg/L | — | Resolved | Dec 31, 2013 | Arsenic Rule |
| Jan 1, 2005 | Dec 31, 2013 | Antimony, Total | MR | No | Yes | — | 0.006 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Antimony, Total | MR | No | Yes | — | 0.006 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Antimony, Total | MR | No | Yes | — | 0.006 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Antimony, Total | MR | No | Yes | — | 0.006 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Fluoride | MR | No | Yes | — | 4.0 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Barium | MR | No | Yes | — | 2 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Barium | MR | No | Yes | — | 2 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Barium | MR | No | Yes | — | 2 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Barium | MR | No | Yes | — | 2 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Cadmium | MR | No | Yes | — | 0.005 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Cadmium | MR | No | Yes | — | 0.005 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Cadmium | MR | No | Yes | — | 0.005 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Chromium | MR | No | Yes | — | 0.1 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Cadmium | MR | No | Yes | — | 0.005 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Fluoride | MR | No | Yes | — | 4.0 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Fluoride | MR | No | Yes | — | 4.0 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Fluoride | MR | No | Yes | — | 4.0 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Chromium | MR | No | Yes | — | 0.1 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Chromium | MR | No | Yes | — | 0.1 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jan 1, 2005 | Dec 31, 2013 | Chromium | MR | No | Yes | — | 0.1 mg/L | — | Resolved | Dec 31, 2013 | Inorganic Chemicals |
| Jun 1, 2004 | — | Lead and Copper Rule | MR | No | No | — | TT | — | Resolved | Aug 14, 2007 | Lead and Copper Rule |
| Jun 1, 2004 | — | Lead and Copper Rule | MR | No | No | — | TT | — | Resolved | Aug 14, 2007 | Lead and Copper 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.