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LYON-SIOUX RWS-BIG SIOUX

PWS ID: IA6000755 · ROCK RAPIDS, Iowa 51246

LYON-SIOUX RWS-BIG SIOUX serves 1,530 people in ROCK RAPIDS, Iowa using Groundwater water sources. It has 71 recorded EPA violations, including 0 health-based violations. PFAS "forever chemicals" were detected in UCMR5 testing (1 compound found).

Water Quality Snapshot: LYON-SIOUX RWS-BIG SIOUX

LYON-SIOUX RWS-BIG SIOUX is a private-owned community water system that delivers drinking water to 1,530 residents in ROCK RAPIDS, Iowa (Lyon County) through 612 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 71 total violations for this system , of which 0 (0%) are health-based — meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 62 monitoring and reporting violations are on file. The most recent violation on record dates to 2019.

The most frequently cited contaminant at this system is Nitrate, recorded in 13 violations (MR). Under EPA's UCMR5 PFAS monitoring program, 1 PFAS compound was detected in samples collected from this system, with a maximum reported concentration of 77 ppt. PFAS are persistent synthetic chemicals linked to health effects at very low exposure levels.

Across Iowa, EPA tracks 1,795 public water systems serving 3,114,444 people, with 138,271 cumulative violations and 27,946 health-based violations on record. About 95% of systems in the state carry at least one violation, and state-wide the average per system is 77 violations. LYON-SIOUX RWS-BIG SIOUX's 71 violations sit below the Iowa average. Statewide, 127 of 152 UCMR5-tested systems have reported PFAS detections (83.6%). All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

PFAS Detected

1 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.

Population Served
1,530
Total Violations
71
Health-Based Violations
0
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Private
Connections
612
County
Lyon
School/Daycare
No
MCL Violations
0
Monitoring Violations
62
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Nitrate MR 13 2010
Lead and Copper Rule MR 5 2004
Nitrite MR 4 2019
Combined Radium (-226 and -228) MR 4 2012
Barium MR 4 2005
Cadmium MR 4 2005
Chromium MR 4 2005
Fluoride MR 4 2005
Mercury MR 4 2005
Selenium MR 4 2005
Thallium, Total MR 4 2005
Arsenic MR 4 2005
Antimony, Total MR 4 2005

PFAS Testing Results (UCMR5)

Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 6 of 180 samples detected PFAS.

Contaminant Date Result MRL Status
PFHxS 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFDA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFOA 4/14/2025 <0.004 µg/L 0.004 µg/L Not Detected
PFOS 4/14/2025 <0.004 µg/L 0.004 µg/L Not Detected
PFNA 4/14/2025 <0.004 µg/L 0.004 µg/L Not Detected
PFDoA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFHpA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFBS 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFTrDA 4/14/2025 <0.007 µg/L 0.007 µg/L Not Detected
PFHxA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
NMeFOSAA 4/14/2025 <0.006 µg/L 0.006 µg/L Not Detected
PFTA 4/14/2025 <0.008 µg/L 0.008 µg/L Not Detected
lithium 4/14/2025 56.0000 µg/L 9 µg/L Detected
NEtFOSAA 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
PFUnA 4/14/2025 <0.002 µg/L 0.002 µg/L Not Detected
11Cl-PF3OUdS 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
9Cl-PF3ONS 4/14/2025 <0.002 µg/L 0.002 µg/L Not Detected
ADONA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFBA 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
6:2 FTS 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
4:2 FTS 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFHpS 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFMPA 4/14/2025 <0.004 µg/L 0.004 µg/L Not Detected
PFPeA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFPeS 4/14/2025 <0.004 µg/L 0.004 µg/L Not Detected
NFDHA 4/14/2025 <0.02 µg/L 0.02 µg/L Not Detected
PFEESA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFMBA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
HFPO-DA 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
8:2 FTS 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
11Cl-PF3OUdS 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
NEtFOSAA 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
PFNA 4/14/2025 <0.004 µg/L 0.004 µg/L Not Detected
PFOS 4/14/2025 <0.004 µg/L 0.004 µg/L Not Detected
PFOA 4/14/2025 <0.004 µg/L 0.004 µg/L Not Detected
PFDA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFDoA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFUnA 4/14/2025 <0.002 µg/L 0.002 µg/L Not Detected
9Cl-PF3ONS 4/14/2025 <0.002 µg/L 0.002 µg/L Not Detected
ADONA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
HFPO-DA 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
PFBA 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
6:2 FTS 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
4:2 FTS 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFHpA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
PFTrDA 4/14/2025 <0.007 µg/L 0.007 µg/L Not Detected
PFHxA 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected
8:2 FTS 4/14/2025 <0.005 µg/L 0.005 µg/L Not Detected
PFTA 4/14/2025 <0.008 µg/L 0.008 µg/L Not Detected
PFHxS 4/14/2025 <0.003 µg/L 0.003 µg/L Not Detected

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records — or to file a complaint, request a Consumer Confidence Report, or check current monitoring status — go directly to the federal and state regulators that enforce the Safe Drinking Water Act for LYON-SIOUX RWS-BIG SIOUX.

Federal Source of Truth

EPA SDWIS — Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID IA6000755 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Iowa Drinking Water Authority

Iowa's primacy agency administers the Safe Drinking Water Act locally. Search EPA SDWIS for the current state contact, or use the state's public health or environment department portal.

Find IA regulator via EPA SDWIS

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2019 Nitrite MR 4 SDWIS / IA6000755 / 1041
2012 Combined Radium (-226 and -228) MR 4 SDWIS / IA6000755 / 4010
2010 Nitrate MR 13 SDWIS / IA6000755 / 1040
2005 Barium MR 4 SDWIS / IA6000755 / 1010
2005 Cadmium MR 4 SDWIS / IA6000755 / 1015
2005 Chromium MR 4 SDWIS / IA6000755 / 1020
2005 Fluoride MR 4 SDWIS / IA6000755 / 1025
2005 Mercury MR 4 SDWIS / IA6000755 / 1035
2005 Selenium MR 4 SDWIS / IA6000755 / 1045
2005 Thallium, Total MR 4 SDWIS / IA6000755 / 1085
2005 Arsenic MR 4 SDWIS / IA6000755 / 1005
2005 Antimony, Total MR 4 SDWIS / IA6000755 / 1074
2004 Lead and Copper Rule MR 5 SDWIS / IA6000755 / 5000

How LYON-SIOUX RWS-BIG SIOUX Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric LYON-SIOUX RWS-BIG SIOUX Iowa avg Federal benchmark
Total violations 71 77 SDWA compliance — any non-zero count is a recorded breach
Health-based violations 0 15.6 Indicates a contaminant exceeded a federal MCL
PFAS detection 1 compound 83.6% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 1,530 1,735 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 1,795 regulated public water systems in Iowa.

Federal MCL reference — Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is LYON-SIOUX RWS-BIG SIOUX water safe to drink? ▼
LYON-SIOUX RWS-BIG SIOUX (PWS ID: IA6000755) has 71 recorded violations in the EPA SDWIS database. PFAS contamination has been detected in UCMR5 testing, with 1 PFAS compound found. This system serves 1,530 people using Groundwater sources.
How many people does LYON-SIOUX RWS-BIG SIOUX serve? ▼
LYON-SIOUX RWS-BIG SIOUX serves 1,530 people in ROCK RAPIDS, Iowa. It is a Private-owned system using Groundwater water sources with 612 service connections.
What type of violations does LYON-SIOUX RWS-BIG SIOUX have? ▼
LYON-SIOUX RWS-BIG SIOUX has 71 total violations: 0 health-based violations (MCL exceedances or treatment failures), 62 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in LYON-SIOUX RWS-BIG SIOUX water? ▼
Yes. UCMR5 testing detected 1 PFAS compound in LYON-SIOUX RWS-BIG SIOUX's water supply: lithium. PFAS are persistent "forever chemicals" that do not break down in the environment.
What water source does LYON-SIOUX RWS-BIG SIOUX use? ▼
LYON-SIOUX RWS-BIG SIOUX uses Groundwater as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.
Where does this data come from? ▼
All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.

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Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. PFAS data from EPA UCMR5 monitoring program (2023-2025). This data is provided for informational purposes only.

Read our methodology — how this data is sourced, computed, and verified.

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Data sourced from $official public datasets. See our methodology for details. Retrieved and formatted by Kiznis Studio Editorial