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Public water system record

Tamoshan

Serves an area of Thurston County, WA · 260 people served

Federal records show 10 health-based violations and 5 monitoring/reporting issues for Tamoshan in the last ten years. The most serious issue in this window was a resolved Haloacetic Acids (HAA5) violation.

  • WA5387140
  • OLYMPIA
  • WA
  • 260 served

System profile

Source water Groundwater
ZIP 98512
EPA system ID WA5387140

Verify this system on EPA ECHO →

Health-based violations, last 10 years
10
Resolved
10
Unresolved
0
Any acute record
No
Monitoring issues, last 10 years
5

Key facts

  • Tamoshan draws water from 2 wells.
  • Highest measured level in the last 10 years: Haloacetic Acids (HAA5), 113.7 µg/L, federal limit 60 µg/L (1.9 times the limit), 2022.
  • Most recent formal enforcement: compliance order (no penalty) by Washington, December 2021.
  • Record on file since 1979, with 1 health-based violation before October 19, 2016.
  • Lead pipe inventory: 0 lead and 69 unknown out of 94 service lines.

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Health-based violations

Since October 2016

Violation data reflects EPA records through March 2026. For the most current status, visit the EPA ECHO database.

Contaminant Rule family Start date Status Acute
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 61 µg/L, federal limit 60 µg/L (at or just above the limit)
 220 Apr 1, 2023 Resolved No
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 76.1 µg/L, federal limit 60 µg/L (1.3 times the limit)
 220 Jan 1, 2023 Resolved No
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 95.4 µg/L, federal limit 60 µg/L (1.6 times the limit)
 220 Oct 1, 2022 Resolved No
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 102.8 µg/L, federal limit 60 µg/L (1.7 times the limit)
 220 Jul 1, 2022 Resolved No
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 107.1 µg/L, federal limit 60 µg/L (1.8 times the limit)
 220 Apr 1, 2022 Resolved No
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 113.7 µg/L, federal limit 60 µg/L (1.9 times the limit)
 220 Jan 1, 2022 Resolved No
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 102.8 µg/L, federal limit 60 µg/L (1.7 times the limit)
 220 Oct 1, 2021 Resolved No
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 100.8 µg/L, federal limit 60 µg/L (1.7 times the limit)
 220 Jul 1, 2021 Resolved No
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 96.2 µg/L, federal limit 80 µg/L (1.2 times the limit)
 220 Apr 1, 2017 Resolved No
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 99.4 µg/L, federal limit 80 µg/L (1.2 times the limit)
 220 Jan 1, 2017 Resolved No

Monitoring and reporting issues

Since October 2016

Missed tests or reports, not contaminants found above a limit.

Issue Start date Status
Revised Total Coliform Rule
Monitoring violation
 Jun 1, 2025 Resolved
Revised Total Coliform Rule
Monitoring violation
 Dec 1, 2021 Resolved
Revised Total Coliform Rule
Monitoring violation
 Nov 1, 2021 Resolved
Haloacetic Acids (HAA5)
Monitoring and reporting
 Oct 1, 2018 Resolved
Total Trihalomethanes (TTHMs)
Monitoring and reporting
 Oct 1, 2018 Resolved

Full record since 1979

EPA's records for Tamoshan go back to 1979. Before October 19, 2016 they list 1 health-based violation (1 archived by EPA without a recorded fix) and 10 monitoring or reporting violations.

Violations that began in Health-based Monitoring and reporting
1970s 0 1
1980s 1 0
1990s 0 6
2000s 0 1
2010 to October 18, 2016 0 2
October 19, 2016 to 2019 2 2
2020s 8 3

Most recent health-based violation before October 19, 2016: Cadmium, began December 1982, Archived.

Show the health-based violation before October 19, 2016
Contaminant Start date Status
Cadmium
Contaminant limit exceeded
 Dec 1, 1982 Archived

Enforcement actions

Washington regulators took 1 formal enforcement action against Tamoshan in 2021. The most recent was a compliance order (no penalty) in December 2021.

Date By Action Violations covered
Dec 2, 2021 Washington Compliance order (no penalty) 8 violations (8 health-based): Haloacetic Acids (HAA5)

What the violations mean

Haloacetic Acids (HAA5)

8 incidents

Haloacetic acid byproducts exceeded the federal limit

Long-term exposure to HAAs may increase cancer risk

Total Trihalomethanes (TTHMs)

2 incidents

Disinfection byproduct levels exceeded the federal limit

Long-term TTHM exposure may increase bladder cancer risk

Where the water comes from

Tamoshan draws water from 2 wells.

Annual water quality report

Tamoshan must give its customers an annual water quality report (Consumer Confidence Report) by July 1, with the levels its tests found in the previous year.

Systems serving 500 or fewer people may meet the rule by telling customers the report is available on request, so you may need to ask Tamoshan for a copy.

Find a posted report with EPA's Consumer Confidence Report search

Testing your own water

To test the water at your tap, or a private well this record does not cover, use a laboratory certified for drinking water by Washington.

Certified drinking water labs by state EPA guidance for private wells