Is Cottage Grove Waterworks Tap Water Safe? Quality Report

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

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	2024-10-17
MCL	Health-based	Archived	1991-09-01 → 1991-09-30
MCL	Health-based	Archived	1991-09-01 → 1991-09-30
MCL	Health-based	Archived	1991-09-01 → 1991-09-30
MCL	Health-based	Archived	1991-09-01 → 1991-09-30
Other	Monitoring	Unaddressed	2024-10-17
MR	Monitoring	Resolved	1997-02-01 → 1997-02-28
MR	Monitoring	Resolved	1997-02-01 → 1997-02-28
MR	Monitoring	Resolved	1997-02-01 → 1997-02-28
MR	Monitoring	Resolved	1997-02-01 → 1997-02-28

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
Fluoride	1260 µg/L 32% of the EPA limit 4000 µg/L worst single sample: 1360 µg/L	101/198	SYR4	2012–2019
Copper	194.65 µg/L 15% of the EPA limit 1300 µg/L worst single sample: 233 µg/L	40/40	SYR4	2014–2017
Lead	0.0023 mg/L 16% of the EPA limit 0.0150 mg/L	14/14	LCR	2023
Bromodichloromethane	2.04 µg/L No EPA limit set worst single sample: 2.1 µg/L	7/21	SYR4	2012–2019
Chloroform	4.44 µg/L No EPA limit set worst single sample: 4.5 µg/L	7/21	SYR4	2012–2019
Lead	13.913 µg/L 93% of the EPA limit 15 µg/L worst single sample: 15.8 µg/L	7/40	SYR4	2014–2017
TTHM	6.922 µg/L 8.7% of the EPA limit 80 µg/L worst single sample: 7.06 µg/L	7/7	SYR4	2013–2019
Barium	12.575 µg/L 0.6% of the EPA limit 2000 µg/L worst single sample: 12.6 µg/L	6/6	SYR4	2014–2017
Combined Radium (-226 And -228)	1.755 pCi/L 35% of the EPA limit 5 pCi/L worst single sample: 1.78 pCi/L	6/6	SYR4	2014
Dibromochloromethane	1.21 µg/L No EPA limit set worst single sample: 1.3 µg/L	6/21	SYR4	2012–2019
Gross Alpha, Excl. Radon And U	7.75 pCi/L 52% of the EPA limit 15 pCi/L worst single sample: 8.12 pCi/L	6/6	SYR4	2014
Gross Beta Particle Activity	4.735 pCi/L No EPA limit set worst single sample: 5.33 pCi/L	6/6	SYR4	2014
Xylenes, Total	2.258 µg/L 0% of the EPA limit 10000 µg/L worst single sample: 2.35 µg/L	2/21	SYR4	2012–2019
Styrene	0.5200 µg/L 0.5% of the EPA limit 100 µg/L	1/21	SYR4	2012–2019

91 contaminants tested, none detected

1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-Dichloroethane1,2-Dichloropropane11Cl-PF3OUdS2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAntimony, TotalArsenicAtrazineBhc-GammaBenzeneBeryllium, TotalBromoformChlorobenzeneCadmiumCarbofuranCarbon TetrachlorideChlordaneChromiumDichloromethaneDalaponDibromoacetic AcidDichloroacetic AcidDinosebDiquatEndothallEndrinEthylbenzeneGlyphosateHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMercuryMethoxychlorMonobromoacetic AcidMonochloroacetic AcidNetfosaaNfdhaNmefosaaNitrateNitrate-NitriteNitriteOxamylPfbaPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfhxaPFHXSPfmbaPfmpaPFNAPFOAPFOSPfpeaPfpesPftaPftrdaPfunaPentachlorophenolPicloramSeleniumSimazineTetrachloroethyleneThallium, TotalTolueneTotal Haloacetic Acids (HAA5)Total Polychlorinated Biphenyls (PCB)ToxapheneTrichloroacetic AcidTrichloroethyleneVinyl Chloridecis-1,2-DichloroethyleneLithiumO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

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Frequently asked questions about Cottage Grove Waterworks

Is Cottage Grove Waterworks tap water safe to drink?

EPA monitoring detected 14 contaminants in Cottage Grove 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 Cottage Grove Waterworks's water?

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

How many people does Cottage Grove Waterworks serve?

Cottage Grove Waterworks reports serving 9,345 people in Wisconsin, per its EPA record.

Has Cottage Grove Waterworks had any water quality violations?

The EPA has 15 violations on file for Cottage Grove Waterworks, of which 5 are health-based (a contaminant limit or required treatment was breached) and 1 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.