Is Assiniboine & Sioux Rural Water Tap Water Safe? Quality Report

Water source: Surface water
Ownership: Federal government

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
TT	Health-based	Resolved	2015-04-01 → 2015-06-30
TT	Health-based	Resolved	2015-01-01 → 2015-03-31
TT	Health-based	Resolved	2014-10-01 → 2014-12-31
TT	Health-based	Resolved	2014-07-01 → 2014-09-30
TT	Health-based	Resolved	2014-04-01 → 2014-06-30
TT	Health-based	Resolved	2013-06-01 → 2013-06-30
TT	Health-based	Resolved	2013-06-01 → 2013-06-30
TT	Health-based	Resolved	2013-06-01 → 2013-06-30
TT	Health-based	Resolved	2013-06-01 → 2013-06-30
TT	Health-based	Resolved	2013-06-01 → 2013-06-30

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
Copper	2042 µg/L 157% of the EPA limit, at the 95th percentile of samples — 1300 µg/L worst single sample: 4010 µg/L	129/133	SYR4	2013–2019
Lead	49.4 µg/L 329% of the EPA limit, at the 95th percentile of samples — 15 µg/L worst single sample: 94 µg/L	33/133	SYR4	2013–2019
TTHM	92 µg/L 115% of the EPA limit, at the 95th percentile of samples — 80 µg/L worst single sample: 129 µg/L	21/21	SYR4	2012–2019
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L	16/16	LCR	2025
Bromodichloromethane	17.05 µg/L No EPA limit set worst single sample: 19 µg/L	14/14	SYR4	2013–2019
Chloroform	44.55 µg/L No EPA limit set worst single sample: 53 µg/L	14/14	SYR4	2013–2019
Dibromochloromethane	5.2 µg/L No EPA limit set	14/14	SYR4	2013–2019
Total Haloacetic Acids (HAA5)	78.1 µg/L 130% of the EPA limit, at the 95th percentile of samples — 60 µg/L worst single sample: 121 µg/L	14/14	SYR4	2012–2019
Nitrate-Nitrite	873 µg/L 8.7% of the EPA limit 10000 µg/L worst single sample: 1500 µg/L	12/12	SYR4	2012–2019
Combined Uranium	2.682 µg/L 8.9% of the EPA limit 30 µg/L	9/10	SYR4	2012–2014
Fluoride	1100 µg/L 28% of the EPA limit 4000 µg/L	9/9	SYR4	2012–2019
Dibromoacetic Acid	1.17 µg/L No EPA limit set worst single sample: 1.2 µg/L	7/7	SYR4	2013–2019
Dichloroacetic Acid	23.2 µg/L No EPA limit set worst single sample: 25 µg/L	7/7	SYR4	2013–2019
Gross Alpha, Excl. Radon And U	5 pCi/L 33% of the EPA limit 15 pCi/L	7/8	SYR4	2012–2014
Trichloroacetic Acid	23.6 µg/L No EPA limit set worst single sample: 26 µg/L	7/7	SYR4	2013–2019
Combined Radium (-226 And -228)	1.475 pCi/L 30% of the EPA limit 5 pCi/L worst single sample: 1.5 pCi/L	6/8	SYR4	2012–2014
Selenium	1.8 µg/L 3.6% of the EPA limit 50 µg/L worst single sample: 2 µg/L	5/9	SYR4	2012–2019
Monochloroacetic Acid	1.57 µg/L No EPA limit set worst single sample: 1.6 µg/L	4/7	SYR4	2013–2019
Monobromoacetic Acid	0.9620 µg/L No EPA limit set worst single sample: 0.9700 µg/L	3/7	SYR4	2013–2019
Nitrate	360 µg/L 3.6% of the EPA limit 10000 µg/L	2/4	SYR4	2012–2013

62 contaminants tested, none detected

1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane2,4,5-TP2,4-DAntimony, TotalArsenicAsbestosAtrazineBhc-GammaBariumBenzeneBenzo(A)PyreneBeryllium, TotalBromoformChlorobenzeneCyanideCadmiumCarbofuranCarbon TetrachlorideChlordaneChromiumDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateHexachlorobenzeneHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMercuryMethoxychlorNitriteOxamylPentachlorophenolPicloramSimazineStyreneTetrachloroethyleneThallium, TotalTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact: WEEKS, ASHLEIGH
Phone: 406-768-5719
Email: [email protected]

Frequently asked questions about Assiniboine & Sioux Rural Water

Is Assiniboine & Sioux Rural Water tap water safe to drink?

EPA monitoring detected 20 contaminants in Assiniboine & Sioux Rural Water'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 Assiniboine & Sioux Rural Water's water?

EPA monitoring detected Copper, Lead, TTHM, Lead, Bromodichloromethane, and others. The full list with the level and data source for each is above.

How many people does Assiniboine & Sioux Rural Water serve?

Assiniboine & Sioux Rural Water reports serving 1,726 people in Montana, per its EPA record.

Has Assiniboine & Sioux Rural Water had any water quality violations?

The EPA has 18 violations on file for Assiniboine & Sioux Rural Water, of which 11 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.