Is Granite Park Water Association Tap Water Safe? Quality Report

Water source: Ground water
Ownership: Private
Counties served: Yellowstone

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

violations on file

still open

Violation	Type	Status	Period
MCL	Health-based	Archived	2024-01-01 → 2024-03-31
MCL	Health-based	Archived	2024-01-01 → 2024-03-31
MCL	Health-based	Archived	2024-01-01 → 2024-03-31
MCL	Health-based	Archived	2024-01-01 → 2024-03-31
Other	Monitoring	Resolved	2023-07-01
Other	Monitoring	Resolved	2023-07-01
MR	Monitoring	Resolved	2023-04-01 → 2023-06-30
MR	Monitoring	Resolved	2023-04-01 → 2023-06-30
MR	Monitoring	Resolved	2023-04-01 → 2023-06-30
MR	Monitoring	Resolved	2023-04-01 → 2023-06-30

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-Nitrite	9935 µg/L 99% of the EPA limit 10000 µg/L worst single sample: 10200 µg/L	66/66	SYR4	2012–2019
Copper	228.25 µg/L 18% of the EPA limit 1300 µg/L worst single sample: 280 µg/L	10/10	SYR4	2014–2017
Lead	0.0020 mg/L 13% of the EPA limit 0.0150 mg/L	9/9	LCR	2023
Dibromochloromethane	8.86 µg/L No EPA limit set worst single sample: 8.9 µg/L	5/5	SYR4	2012–2018
Lead	13.6 µg/L 91% of the EPA limit 15 µg/L worst single sample: 16 µg/L	5/10	SYR4	2014–2017
TTHM	20.8 µg/L 26% of the EPA limit 80 µg/L worst single sample: 21 µg/L	5/5	SYR4	2012–2018
Bromodichloromethane	5.45 µg/L No EPA limit set worst single sample: 5.6 µg/L	4/5	SYR4	2012–2018
Bromoform	4.91 µg/L No EPA limit set worst single sample: 5 µg/L	3/5	SYR4	2012–2018
Chloroform	2 µg/L No EPA limit set	3/5	SYR4	2012–2018
Dibromoacetic Acid	4.77 µg/L No EPA limit set worst single sample: 4.9 µg/L	3/3	SYR4	2012–2018
Total Haloacetic Acids (HAA5)	6.83 µg/L 11% of the EPA limit 60 µg/L worst single sample: 7 µg/L	3/3	SYR4	2012–2018
Combined Uranium	17.85 µg/L 60% of the EPA limit 30 µg/L worst single sample: 18 µg/L	2/2	SYR4	2014–2018
Dichloroacetic Acid	1.58 µg/L No EPA limit set worst single sample: 1.6 µg/L	2/3	SYR4	2012–2018
Fluoride	500 µg/L 13% of the EPA limit 4000 µg/L	2/2	SYR4	2014–2017
Selenium	1.95 µg/L 3.9% of the EPA limit 50 µg/L worst single sample: 2 µg/L	2/2	SYR4	2014–2017
Trichloroacetic Acid	0.5870 µg/L No EPA limit set worst single sample: 0.5900 µg/L	2/3	SYR4	2012–2018
Arsenic	1 µg/L 10% of the EPA limit 10 µg/L	1/2	SYR4	2014–2017
Di(2-ethylhexyl) Phthalate	2.1 µg/L 35% of the EPA limit 6 µg/L	1/5	SYR4	2014–2017
Gross Alpha, Excl. Radon And U	9.1 pCi/L 61% of the EPA limit 15 pCi/L	1/2	SYR4	2014–2018
Monobromoacetic Acid	0.5500 µg/L No EPA limit set	1/3	SYR4	2012–2018

51 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, TotalAtrazineBhc-GammaBariumBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCadmiumCarbofuranCarbon TetrachlorideChlordaneChromiumDichloromethaneDalaponDi(2-ethylhexyl) AdipateDinosebEndrinEthylbenzeneHexachlorobenzeneHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMercuryMethoxychlorMonochloroacetic AcidOxamylPentachlorophenolPicloramSimazineStyreneTetrachloroethyleneThallium, TotalTolueneToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact: STONE, SPENCER M
Phone: 406-652-5523
Email: [email protected]

Frequently asked questions about Granite Park Water Association

Is Granite Park Water Association tap water safe to drink?

EPA monitoring detected 20 contaminants in Granite Park Water Association'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 Granite Park Water Association's water?

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

How many people does Granite Park Water Association serve?

Granite Park Water Association reports serving 250 people in Montana, per its EPA record.

Has Granite Park Water Association had any water quality violations?

The EPA has 49 violations on file for Granite Park Water Association, of which 4 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.