TAMOSHAN
PWS ID: WA5387140 · Olympia, Washington 98512
TAMOSHAN serves 260 people in Olympia, Washington using Groundwater water sources. It has 42 recorded EPA violations, including 23 health-based violations. No PFAS contamination was detected in UCMR5 testing.
Water Quality Snapshot: TAMOSHAN
TAMOSHAN is a local-owned community water system that delivers drinking water to 260 residents in Olympia, Washington (Thurston County) through 94 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 42 total violations for this system , of which 23 (55%) are health-based — meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 13 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 16 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 Washington, EPA tracks 4,557 public water systems serving 9,736,844 people, with 314,648 cumulative violations and 20,590 health-based violations on record. About 92% of systems in the state carry at least one violation, and state-wide the average per system is 69 violations. TAMOSHAN's 42 violations sit below the Washington average. Statewide, 98 of 247 UCMR5-tested systems have reported PFAS detections (39.7%). All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 94
- County
- Thurston
- School/Daycare
- No
- MCL Violations
- 23
- Monitoring Violations
- 13
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Total Haloacetic Acids (HAA5) | MCL | 16 | 2023 |
| TTHM | MCL | 6 | 2017 |
| Coliform (TCR) | MR | 5 | 1999 |
| Revised Total Coliform Rule | MON | 3 | 2025 |
| Lead and Copper Rule | MR | 2 | 2000 |
| Consumer Confidence Rule | Other | 2 | 2016 |
| TTHM | MR | 1 | 2018 |
| Gross Alpha, Excl. Radon and U | MR | 1 | 1979 |
| Cadmium | MCL | 1 | 1982 |
| Total Haloacetic Acids (HAA5) | MR | 1 | 2018 |
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 TAMOSHAN.
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 WA5387140 on SDWISSource: EPA SDWIS Federal Reports Search
Washington Drinking Water Authority
Washington State Department of Health — Office of Drinking Water is the primacy agency that licenses and inspects TAMOSHAN under EPA-delegated authority.
Open WA regulator portalSource: Washington State Department of Health — Office of Drinking Water
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 | Revised Total Coliform Rule | MON | 3 | SDWIS / WA5387140 / 8000 |
| 2023 | Total Haloacetic Acids (HAA5) | MCL | 16 | SDWIS / WA5387140 / 2456 |
| 2018 | TTHM | MR | 1 | SDWIS / WA5387140 / 2950 |
| 2018 | Total Haloacetic Acids (HAA5) | MR | 1 | SDWIS / WA5387140 / 2456 |
| 2017 | TTHM | MCL | 6 | SDWIS / WA5387140 / 2950 |
| 2016 | Consumer Confidence Rule | Other | 2 | SDWIS / WA5387140 / 7000 |
| 2000 | Lead and Copper Rule | MR | 2 | SDWIS / WA5387140 / 5000 |
| 1999 | Coliform (TCR) | MR | 5 | SDWIS / WA5387140 / 3100 |
| 1982 | Cadmium | MCL | 1 | SDWIS / WA5387140 / 1015 |
| 1979 | Gross Alpha, Excl. Radon and U | MR | 1 | SDWIS / WA5387140 / 4000 |
How TAMOSHAN Compares
Cross-reference this system's record against state averages and the federal MCL framework for context.
| Metric | TAMOSHAN | Washington avg | Federal benchmark |
|---|---|---|---|
| Total violations | 42 | 69 | SDWA compliance — any non-zero count is a recorded breach |
| Health-based violations | 23 | 4.5 | Indicates a contaminant exceeded a federal MCL |
| PFAS detection | None | 39.7% | EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt |
| Population served | 260 | 2,137 | Sizing context for compliance burden |
Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 4,557 regulated public water systems in Washington.
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 TAMOSHAN water safe to drink? ▼
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What type of violations does TAMOSHAN have? ▼
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Related Data for Washington
Read our methodology — how this data is sourced, computed, and verified.