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States → EPA Region 9 — Tribal Water Systems

Community Water System · PWS 090605143

Yurok - Terwer Water System

Klamath, EPA Region 9 — Tribal Water Systems 95548 - drinking water served from groundwater sources to 300 people, tracked in EPA SDWIS and UCMR5.

300
People served
180
EPA violations
4
Health-based
Untested
UCMR5 result

The verdict

EPA records 180 drinking-water violations at Yurok - Terwer Water System, 2% of them health-based.

180
Total EPA violations on record
2%
Health-based (MCL / treatment failure)
300
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Yurok - Terwer Water System

Yurok - Terwer Water System is a native american-owned community water system that delivers drinking water to 300 residents in Klamath, EPA Region 9 — Tribal Water Systems through 160 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 180 total violations for this system , of which 4 (2%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 154 monitoring and reporting violations are on file. The most recent violation on record dates to 2024.

The most frequently cited contaminant at this system is Coliform (TCR), recorded in 10 violations (MR). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

EPA Region 9 — Tribal Water Systems has thousands of regulated public water systems tracked by EPA under the Safe Drinking Water Act.

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
300
Total Violations
180
Health-Based Violations
4
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Native American
Connections
160
School/Daycare
No
MCL Violations
4
Monitoring Violations
154
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Coliform (TCR) MR 10 2016
Lead and Copper Rule MR 10 2024
Nitrate MR 7 2015
Revised Total Coliform Rule MON 5 2024
Coliform (TCR) MCL 4 2002
Endothall MR 3 2011
Consumer Confidence Rule Other 3 2024
Fluoride MR 2 2011
Endrin MR 2 2011
BHC-GAMMA MR 2 2011
Methoxychlor MR 2 2011
Toxaphene MR 2 2011
Dalapon MR 2 2011
Diquat MR 2 2011
Glyphosate MR 2 2011
Di(2-ethylhexyl) adipate MR 2 2011
OXAMYL MR 2 2011
Simazine MR 2 2011
Dinoseb MR 2 2011
Hexachlorocyclopentadiene MR 2 2011
Carbofuran MR 2 2011
Atrazine MR 2 2011
Heptachlor MR 2 2011
Heptachlor epoxide MR 2 2011
2,4,5-TP MR 2 2011
Benzo(a)pyrene MR 2 2011
Pentachlorophenol MR 2 2011
1,2,4-Trichlorobenzene MR 2 2011
cis-1,2-Dichloroethylene MR 2 2011
Total Polychlorinated Biphenyls (PCB) MR 2 2011

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 Yurok - Terwer Water System.

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 090605143 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

EPA Region 9 — Tribal Water Systems Drinking Water Authority

EPA Region 9 — Tribal Water Systems'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 09 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
2024 Lead and Copper Rule MR 10 SDWIS / 090605143 / 5000
2024 Revised Total Coliform Rule MON 5 SDWIS / 090605143 / 8000
2024 Consumer Confidence Rule Other 3 SDWIS / 090605143 / 7000
2024 Chlorine MR 2 SDWIS / 090605143 / 0999
2024 Public Notice Other 1 SDWIS / 090605143 / 7500
2016 Coliform (TCR) MR 10 SDWIS / 090605143 / 3100
2016 E. COLI MR 1 SDWIS / 090605143 / 3014
2015 Nitrate MR 7 SDWIS / 090605143 / 1040
2011 Endothall MR 3 SDWIS / 090605143 / 2033
2011 Fluoride MR 2 SDWIS / 090605143 / 1025
2011 Endrin MR 2 SDWIS / 090605143 / 2005
2011 BHC-GAMMA MR 2 SDWIS / 090605143 / 2010
2011 Methoxychlor MR 2 SDWIS / 090605143 / 2015
2011 Toxaphene MR 2 SDWIS / 090605143 / 2020
2011 Dalapon MR 2 SDWIS / 090605143 / 2031

How Yurok - Terwer Water System Compares

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

Metric Yurok - Terwer Water System EPA Region 9 — Tribal Water Systems avg Federal benchmark
Total violations 180 - SDWA compliance, any non-zero count is a recorded breach
Health-based violations 4 - Indicates a contaminant exceeded a federal MCL
PFAS detection None - EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 300 - Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across all regulated public water systems in EPA Region 9 — Tribal Water Systems.

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 Yurok - Terwer Water System water safe to drink? ▼
Yurok - Terwer Water System (PWS ID: 090605143) has 180 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 300 people using Groundwater sources.
How many people does Yurok - Terwer Water System serve? ▼
Yurok - Terwer Water System serves 300 people in Klamath, EPA Region 9 — Tribal Water Systems. It is a Native American-owned system using Groundwater water sources with 160 service connections.
What type of violations does Yurok - Terwer Water System have? ▼
Yurok - Terwer Water System has 180 total violations: 4 health-based violations (MCL exceedances or treatment failures), 154 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Yurok - Terwer Water System water? ▼
No PFAS testing data is available for Yurok - Terwer Water System under the EPA's UCMR5 monitoring program.
What water source does Yurok - Terwer Water System use? ▼
Yurok - Terwer Water System 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.