Thurston County Water Quality: 3 Cities Ranked by the Records
Thurston County, Washington: 3 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.
Highest result for each contaminant
One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.
Perfluorooctanesulfonic acid (PFOS)Detected in 1 system of 3 tested4.0 ng/L federal MCL (2024) · US EPAHighest5.8 ng/L
- OLYMPIA CITY OF5.8 ng/LSample date: 2023-10-18 to 2024-04-23
- LACEY WATER DEPARTMENTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-12-13 to 2025-11-24
- YELM CITY OFNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-10-17 to 2025-04-03
Perfluorooctanoic acid (PFOA)Detected in 1 system of 3 tested4.0 ng/L federal MCL (2024) · US EPAHighest4.3 ng/L
- OLYMPIA CITY OF4.3 ng/LSample date: 2023-10-18 to 2024-04-23
- LACEY WATER DEPARTMENTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-12-13 to 2025-11-24
- YELM CITY OFNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-10-17 to 2025-04-03
Lead (90th percentile)Detected in 3 systems15 µg/L federal action level · US EPAHighest6 µg/L
- LACEY WATER DEPARTMENT6 µg/LMonitoring period: 2016–2016
- OLYMPIA CITY OF3.4 µg/LMonitoring period: 2023–2025
- YELM CITY OF1.9 µg/LMonitoring period: 2022–2024
Perfluorohexanesulfonic acid (PFHxS)Detected in 1 system of 3 tested10 ng/L federal MCL (2024) · US EPAHighest3.1 ng/L
- LACEY WATER DEPARTMENT3.1 ng/LSample date: 2023-12-13 to 2025-11-24
- OLYMPIA CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-10-18 to 2024-04-23
- YELM CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-10-17 to 2025-04-03
Perfluorobutanesulfonic acid (PFBS)Detected in 2 systems of 3 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest4.8 ng/L
- OLYMPIA CITY OF4.8 ng/LSample date: 2023-10-18 to 2024-04-23
- LACEY WATER DEPARTMENT4.2 ng/LSample date: 2023-12-13 to 2025-11-24
- YELM CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-10-17 to 2025-04-03
Perfluorohexanoic acid (PFHxA)Detected in 2 systems of 3 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest9.8 ng/L
- LACEY WATER DEPARTMENT9.8 ng/LSample date: 2023-12-13 to 2025-11-24
- OLYMPIA CITY OF4 ng/LSample date: 2023-10-18 to 2024-04-23
- YELM CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-10-17 to 2025-04-03
Perfluoropentanoic acid (PFPeA)Detected in 2 systems of 3 testedNo federal or state limit; shown for transparencyHighest18.8 ng/L
- LACEY WATER DEPARTMENT18.8 ng/LSample date: 2023-12-13 to 2025-11-24
- OLYMPIA CITY OF3.3 ng/LSample date: 2023-10-18 to 2024-04-23
- YELM CITY OFNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-10-17 to 2025-04-03
24 substances tested, none detected in any systemShow
Tested in these 3 systems: LACEY WATER DEPARTMENT, OLYMPIA CITY OF, YELM CITY OF
- 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
- 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
- 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
- 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
- 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
- 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
- Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
- Lithium
- N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
- N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
- Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
- Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
- Perfluoro-3-methoxypropanoic acid (PFMPA)
- Perfluoro-4-methoxybutanoic acid (PFMBA)
- Perfluorobutanoic acid (PFBA)
- Perfluorodecanoic acid (PFDA)
- Perfluorododecanoic acid (PFDoA)
- Perfluoroheptanesulfonic acid (PFHpS)
- Perfluoroheptanoic acid (PFHpA)
- Perfluorononanoic acid (PFNA)
- Perfluoropentanesulfonic acid (PFPeS)
- Perfluorotetradecanoic acid (PFTA)
- Perfluorotridecanoic acid (PFTrDA)
- Perfluoroundecanoic acid (PFUnA)
Cities ranked by the records
Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.
0of 3 cities above the 15 µg/L action level
Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.
Lead in WashingtonLargest water systems
Frequently asked
How does Thurston County tap water compare across cities?
PurityMap ranks 3 cities in Thurston County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Yelm's main water system: YELM CITY OF · PWSID WA5399350 · Purity Score 98 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.
How many Thurston County cities had a PFAS sample above a 2024 EPA limit?
1 of 3 Thurston County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Olympia (PFOS 5.8 ng/L). That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation. PFAS were detected at any level in 2.
Is there lead in Thurston County tap water?
Utilities report lead as a 90th-percentile result from home taps. 3 of 3 Thurston County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.
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