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Tap water quality report

Diablo Wtr Sys-Seattle City Light

EPA monitoring tested this supplier for 70 contaminants and detected 5. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

70
contaminants tested
5
detected
53
people served
2
health-based violations
Washington rankingsLead in WashingtonPFAS in Washington
Water source
Ground water
Ownership
Local government
Counties served
Whatcom

Compliance record

Formal violations the EPA has on file for this supplier. A health-based violation means a contaminant limit or a required treatment was breached; the rest are monitoring or reporting failures — still violations, but not a measured health risk.

2
health-based violations
33
violations on file
0
still open
ViolationTypeStatusPeriod
TT Health-based Resolved 2025-10-23
MCL Health-based Archived 1992-11-01 → 1992-11-30
Other Monitoring Resolved 2024-07-01
MR Monitoring Resolved 2022-01-01 → 2022-12-31
Other Monitoring Resolved 2021-07-01
MR Monitoring Resolved 2021-01-01 → 2023-12-31
MR Monitoring Resolved 2021-01-01 → 2023-12-31
Other Monitoring Resolved 2013-07-01
Other Monitoring Resolved 2011-07-01
MR Monitoring Resolved 2006-01-01

Other contaminants detected

Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the 95th percentile of this system's samples — over 100% is worth reading, but is not by itself a violation. Where a single sample came in higher than that percentile, it is noted under the bar. Formal violations are listed separately.
ContaminantLevel vs EPA limitDetection rateSourcePeriod
Nitrate
240 µg/L 2.4%
of the EPA limit 10000 µg/L
 16/16 SYR4 2012–2019
Lead
0.0155 mg/L 103%
above the EPA limit of 0.0150 mg/L
 10/10 LCR 2024
Barium
7 µg/L 0.4%
of the EPA limit 2000 µg/L
 1/1 SYR4 2018
Copper
6 µg/L 0.5%
of the EPA limit 1300 µg/L
 1/1 SYR4 2018
Nitrate-Nitrite
160 µg/L 1.6%
of the EPA limit 10000 µg/L
 1/1 SYR4 2018
65 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-Dichloroethane1,2-Dichloropropane2,4,5-TP2,4-DAntimony, TotalArsenicAtrazineBhc-GammaBenzeneBenzo(A)PyreneBeryllium, TotalBromodichloromethaneBromoformChlorobenzeneCyanideCadmiumCarbon TetrachlorideChlordaneChloroformChromiumDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDibromoacetic AcidDibromochloromethaneDichloroacetic AcidDinosebEndrinEthylbenzeneFluorideGross Beta Particle ActivityHexachlorobenzeneHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoLeadMercuryMethoxychlorMonobromoacetic AcidMonochloroacetic AcidNitritePentachlorophenolPicloramSeleniumSimazineStyreneTetrachloroethyleneThallium, TotalTolueneTotal Haloacetic Acids (HAA5)ToxapheneTrichloroacetic AcidTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact
Kevin Wynn

Frequently asked questions about Diablo Wtr Sys-Seattle City Light

Is Diablo Wtr Sys-Seattle City Light tap water safe to drink?

EPA monitoring detected 5 contaminants in Diablo Wtr Sys-Seattle City Light's water. A detection isn't the same as a violation — most levels are within federal limits. See each level and source above, and the utility's annual Consumer Confidence Report for its official compliance status.

What contaminants were detected in Diablo Wtr Sys-Seattle City Light's water?

EPA monitoring detected Nitrate, Lead, Barium, Copper, Nitrate-Nitrite. The full list with the level and data source for each is above.

How many people does Diablo Wtr Sys-Seattle City Light serve?

Diablo Wtr Sys-Seattle City Light reports serving 53 people in Washington, per its EPA record.

Has Diablo Wtr Sys-Seattle City Light had any water quality violations?

The EPA has 33 violations on file for Diablo Wtr Sys-Seattle City Light, of which 2 are health-based (a contaminant limit or required treatment was breached) and 0 remain open. The rest are monitoring or reporting failures.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.