Is Onalaska Waterworks Tap Water Safe? Quality Report

Water source: Ground water
Ownership: Local government
Counties served: La Crosse

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	Resolved	2010-07-01 → 2010-07-31
MCL	Health-based	Resolved	2010-07-01 → 2010-07-31
MCL	Health-based	Resolved	2010-07-01 → 2010-07-31
MCL	Health-based	Resolved	2010-07-01 → 2010-07-31
MCL	Health-based	Resolved	1997-08-01 → 1997-08-31
MCL	Health-based	Resolved	1997-08-01 → 1997-08-31
MCL	Health-based	Resolved	1997-08-01 → 1997-08-31
MCL	Health-based	Resolved	1997-08-01 → 1997-08-31
MR	Monitoring	Resolved	2001-01-01 → 2001-03-31
MR	Monitoring	Resolved	2001-01-01 → 2001-03-31

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	6400 µg/L 64% of the EPA limit 10000 µg/L worst single sample: 9950 µg/L	216/218	SYR4	2012–2019
Fluoride	840.2 µg/L 21% of the EPA limit 4000 µg/L worst single sample: 861 µg/L	104/199	SYR4	2012–2019
Copper	1373 µg/L 106% of the EPA limit, at the 95th percentile of samples — 1300 µg/L worst single sample: 1660 µg/L	59/61	SYR4	2014–2017
Chloroform	3.7495 µg/L No EPA limit set worst single sample: 3.77 µg/L	22/43	SYR4	2012–2019
Monochloroacetic Acid	109.775 µg/L No EPA limit set worst single sample: 113 µg/L	22/22	SYR4	2012–2019
Total Haloacetic Acids (HAA5)	112.921 µg/L 188% of the EPA limit, at the 95th percentile of samples — 60 µg/L worst single sample: 116.193 µg/L	22/22	SYR4	2012–2019
Bromodichloromethane	3.99 µg/L No EPA limit set worst single sample: 4.07 µg/L	21/43	SYR4	2012–2019
Lead	3.5015 µg/L 23% of the EPA limit 15 µg/L worst single sample: 6 µg/L	20/61	SYR4	2014–2017
TTHM	11.3852 µg/L 14% of the EPA limit 80 µg/L worst single sample: 11.655 µg/L	20/20	SYR4	2012–2019
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L	19/19	LCR	2023
Dibromochloromethane	3.251 µg/L No EPA limit set worst single sample: 3.29 µg/L	14/43	SYR4	2012–2019
Trichloroacetic Acid	1.5855 µg/L No EPA limit set worst single sample: 2.32 µg/L	14/22	SYR4	2012–2019
Barium	97.68 µg/L 4.9% of the EPA limit 2000 µg/L worst single sample: 107 µg/L	9/9	SYR4	2014–2017
Dibromoacetic Acid	1.042 µg/L No EPA limit set worst single sample: 1.09 µg/L	9/22	SYR4	2012–2019
Dichloroacetic Acid	2.974 µg/L No EPA limit set worst single sample: 3.03 µg/L	9/22	SYR4	2012–2019
Nitrate-Nitrite	8450 µg/L 85% of the EPA limit 10000 µg/L worst single sample: 9950 µg/L	9/9	SYR4	2014–2017
Tetrachloroethylene	0.6831 µg/L 14% of the EPA limit 5 µg/L worst single sample: 0.6960 µg/L	7/23	SYR4	2014–2019
Bromoform	1.155 µg/L No EPA limit set worst single sample: 1.17 µg/L	6/43	SYR4	2012–2019
Combined Radium (-226 And -228)	3.092 pCi/L 62% of the EPA limit 5 pCi/L worst single sample: 3.25 pCi/L	5/5	SYR4	2014–2017
Gross Alpha, Excl. Radon And U	2.71 pCi/L 18% of the EPA limit 15 pCi/L worst single sample: 2.8 pCi/L	4/4	SYR4	2014
Arsenic	1 µg/L 10% of the EPA limit 10 µg/L	3/9	SYR4	2014–2017
Mercury	0.4000 µg/L 20% of the EPA limit 2 µg/L	2/9	SYR4	2014–2017
Monobromoacetic Acid	0.4990 µg/L No EPA limit set worst single sample: 0.5000 µg/L	2/22	SYR4	2012–2019
Combined Uranium	0.5000 µg/L 1.7% of the EPA limit 30 µg/L	1/1	SYR4	2017
Selenium	0.6000 µg/L 1.2% of the EPA limit 50 µg/L	1/9	SYR4	2014–2017
Thallium, Total	0.5000 µg/L 25% of the EPA limit 2 µg/L	1/9	SYR4	2014–2017

48 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-GammaBenzeneBeryllium, TotalChlorobenzeneCadmiumCarbofuranCarbon TetrachlorideChlordaneChromiumDichloromethaneDalaponDinosebDiquatEndothallEndrinEthylbenzeneGlyphosateHexachlorobenzeneHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMethoxychlorNitriteOxamylPentachlorophenolPicloramSimazineStyreneTolueneToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

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Frequently asked questions about Onalaska Waterworks

Is Onalaska Waterworks tap water safe to drink?

EPA monitoring detected 26 contaminants in Onalaska Waterworks'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 Onalaska Waterworks's water?

EPA monitoring detected Nitrate, Fluoride, Copper, Chloroform, Monochloroacetic Acid, and others. The full list with the level and data source for each is above.

How many people does Onalaska Waterworks serve?

Onalaska Waterworks reports serving 18,000 people in Wisconsin, per its EPA record.

Has Onalaska Waterworks had any water quality violations?

The EPA has 12 violations on file for Onalaska Waterworks, of which 8 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.