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Community Water System · PWS ID5070020

Greenhorn Subd

Ketchum, Idaho 83340 - drinking water served from groundwater sources to 75 people, tracked in EPA SDWIS and UCMR5.

75
People served
105
EPA violations
51
Health-based
Untested
UCMR5 result

The verdict

EPA records 105 drinking-water violations at Greenhorn Subd, 49% of them health-based - above the Idaho per-system average.

105
Total EPA violations on record
49%
Health-based (MCL / treatment failure)
75
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Greenhorn Subd

Greenhorn Subd is a private-owned community water system that delivers drinking water to 75 residents in Ketchum, Idaho (Blaine County) through 29 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 105 total violations for this system , of which 51 (49%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 52 monitoring and reporting violations are on file. The most recent violation on record dates to 2025.

The most frequently cited contaminant at this system is Total Haloacetic Acids (HAA5), recorded in 30 violations (MCL, health-based). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

Across Idaho, EPA tracks 2,005 public water systems serving 1,743,912 people, with 104,850 cumulative violations and 19,965 health-based violations on record. About 96% of systems in the state carry at least one violation, and state-wide the average per system is 52.3 violations. Statewide, 40 of 60 UCMR5-tested systems have reported PFAS detections (66.7%).

Greenhorn Subd's 105 violations sit above the Idaho average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

Population Served
75
Total Violations
105
Health-Based Violations
51
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Private
Connections
29
County
Blaine
School/Daycare
No
MCL Violations
51
Monitoring Violations
52
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Total Haloacetic Acids (HAA5) MCL 30 2020
Coliform (TCR) MR 20 2005
Coliform (TCR) MCL 16 2013
Lead and Copper Rule MR 8 2024
Groundwater Rule MR 6 2024
Chlorine MR 6 2024
Revised Total Coliform Rule MCL 5 2017
TTHM MR 3 2017
Total Haloacetic Acids (HAA5) MR 3 2017
Revised Total Coliform Rule MON 3 2023
Nitrite MR 2 1993
LEAD AND COPPER RULE REVISIONS RPT 2 2025
Nitrate MR 1 1999

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 Greenhorn Subd.

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 ID5070020 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Idaho Drinking Water Authority

Idaho'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 ID 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
2025 LEAD AND COPPER RULE REVISIONS RPT 2 SDWIS / ID5070020 / 5200
2024 Lead and Copper Rule MR 8 SDWIS / ID5070020 / 5000
2024 Groundwater Rule MR 6 SDWIS / ID5070020 / 0700
2024 Chlorine MR 6 SDWIS / ID5070020 / 0999
2023 Revised Total Coliform Rule MON 3 SDWIS / ID5070020 / 8000
2020 Total Haloacetic Acids (HAA5) MCL 30 SDWIS / ID5070020 / 2456
2017 Revised Total Coliform Rule MCL 5 SDWIS / ID5070020 / 8000
2017 TTHM MR 3 SDWIS / ID5070020 / 2950
2017 Total Haloacetic Acids (HAA5) MR 3 SDWIS / ID5070020 / 2456
2013 Coliform (TCR) MCL 16 SDWIS / ID5070020 / 3100
2005 Coliform (TCR) MR 20 SDWIS / ID5070020 / 3100
1999 Nitrate MR 1 SDWIS / ID5070020 / 1040
1993 Nitrite MR 2 SDWIS / ID5070020 / 1041

How Greenhorn Subd Compares

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

Metric Greenhorn Subd Idaho avg Federal benchmark
Total violations 105 52.3 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 51 10 Indicates a contaminant exceeded a federal MCL
PFAS detection None 66.7% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 75 870 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 2,005 regulated public water systems in Idaho.

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 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Greenhorn Subd water safe to drink? ▼
Greenhorn Subd (PWS ID: ID5070020) has 105 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 75 people using Groundwater sources.
How many people does Greenhorn Subd serve? ▼
Greenhorn Subd serves 75 people in Ketchum, Idaho. It is a Private-owned system using Groundwater water sources with 29 service connections.
What type of violations does Greenhorn Subd have? ▼
Greenhorn Subd has 105 total violations: 51 health-based violations (MCL exceedances or treatment failures), 52 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Greenhorn Subd water? ▼
No PFAS testing data is available for Greenhorn Subd under the EPA's UCMR5 monitoring program.
What water source does Greenhorn Subd use? ▼
Greenhorn Subd 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.
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. This data is provided for informational purposes only.

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

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.