Is Yak Co - Terrace Heights Tap Water Safe? Quality Report

Water source: Ground water
Ownership: Local government
Counties served: Yakima

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.

health-based violations

194

violations on file

still open

Violation	Type	Status	Period
MCL	Health-based	Resolved	2023-08-01 → 2023-08-31
MCL	Health-based	Archived	1993-07-01 → 1993-07-31
MR	Monitoring	Resolved	2025-01-01 → 2025-12-31
MR	Monitoring	Resolved	2025-01-01 → 2025-12-31
MR	Monitoring	Resolved	2025-01-01 → 2025-12-31
MON	Monitoring	Resolved	2022-10-01 → 2022-10-31
MR	Monitoring	Resolved	2020-01-01 → 2025-12-31
MR	Monitoring	Resolved	2020-01-01 → 2025-12-31
MR	Monitoring	Resolved	2020-01-01 → 2025-12-31
MR	Monitoring	Resolved	2020-01-01 → 2025-12-31

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.

Contaminant	Level vs EPA limit	Detection rate	Source	Period
Nitrate	2410 µg/L 24% of the EPA limit 10000 µg/L worst single sample: 2550 µg/L	54/72	SYR4	2012–2019
Nitrate-Nitrite	2395 µg/L 24% of the EPA limit 10000 µg/L worst single sample: 2550 µg/L	27/36	SYR4	2012–2019
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L	11/11	LCR	2023
Bromoform	8.1055 µg/L No EPA limit set worst single sample: 8.9 µg/L	8/17	SYR4	2013–2019
Chloroform	6.69 µg/L No EPA limit set worst single sample: 9 µg/L	8/17	SYR4	2013–2019
Dibromochloromethane	5.595 µg/L No EPA limit set worst single sample: 5.7 µg/L	8/17	SYR4	2013–2019
TTHM	18.815 µg/L 24% of the EPA limit 80 µg/L worst single sample: 19.9 µg/L	8/8	SYR4	2013–2019
Bromodichloromethane	5.72 µg/L No EPA limit set worst single sample: 6.2 µg/L	7/17	SYR4	2013–2019
Arsenic	4.766 µg/L 48% of the EPA limit 10 µg/L worst single sample: 4.79 µg/L	5/5	SYR4	2016–2019
Barium	69.942 µg/L 3.5% of the EPA limit 2000 µg/L worst single sample: 76.14 µg/L	5/5	SYR4	2016–2019
Copper	3.514 µg/L 0.3% of the EPA limit 1300 µg/L worst single sample: 3.99 µg/L	5/5	SYR4	2016–2019
Fluoride	710 µg/L 18% of the EPA limit 4000 µg/L worst single sample: 790 µg/L	5/5	SYR4	2016–2019
Thallium, Total	0.6440 µg/L 32% of the EPA limit 2 µg/L worst single sample: 0.7200 µg/L	5/5	SYR4	2016–2019
Chromium	2.667 µg/L 2.7% of the EPA limit 100 µg/L worst single sample: 2.79 µg/L	4/5	SYR4	2016–2019
Lead	2.267 µg/L 15% of the EPA limit 15 µg/L worst single sample: 2.48 µg/L	3/5	SYR4	2016–2019
Selenium	1.076 µg/L 2.2% of the EPA limit 50 µg/L worst single sample: 1.08 µg/L	3/5	SYR4	2016–2019
Antimony, Total	0.1285 µg/L 2.1% of the EPA limit 6 µg/L worst single sample: 0.1300 µg/L	2/5	SYR4	2016–2019
Total Haloacetic Acids (HAA5)	5.385 µg/L 9% of the EPA limit 60 µg/L worst single sample: 5.6 µg/L	2/9	SYR4	2013–2018
Lithium	12.9 µg/L No EPA limit set	2/10	UCMR-5	2025
Dibromoacetic Acid	1.3 µg/L No EPA limit set	1/10	SYR4	2013–2019
Dichloroacetic Acid	3.8 µg/L No EPA limit set	1/10	SYR4	2013–2019
Trichloroacetic Acid	1.8 µg/L No EPA limit set	1/10	SYR4	2013–2019

81 contaminants tested, none detected

1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane11Cl-PF3OUdS2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAtrazineBhc-GammaBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCyanideCadmiumCarbon TetrachlorideChlordaneDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebEthylene DibromideEndrinEthylbenzeneHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMercuryMethoxychlorMonobromoacetic AcidMonochloroacetic AcidNetfosaaNfdhaNmefosaaNitritePfbaPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfhxaPFHXSPfmbaPfmpaPFNAPFOAPFOSPfpeaPfpesPftaPftrdaPfunaPentachlorophenolPicloramSimazineStyreneTetrachloroethyleneTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact: Gene Buermann

Frequently asked questions about Yak Co - Terrace Heights

Is Yak Co - Terrace Heights tap water safe to drink?

EPA monitoring detected 22 contaminants in Yak Co - Terrace Heights'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 Yak Co - Terrace Heights's water?

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

How many people does Yak Co - Terrace Heights serve?

Yak Co - Terrace Heights reports serving 8,410 people in Washington, per its EPA record.

Has Yak Co - Terrace Heights had any water quality violations?

The EPA has 194 violations on file for Yak Co - Terrace Heights, 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.