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Water Quality Report

Cottage Grove, WI

Dane County · 9,345 residents · 1 water system

9

Contaminants detected

0

PFAS compounds

358

Hardness (mg/L)

0

Above legal limits

2

Above health guidelines

Cottage Grove drinking water comes from groundwater wells. Based on the most recent monitoring data, 9 contaminants have been detected in the water supply, including Lead, Arsenic, Copper, Radium, and 5 others. PFAS testing has been conducted with no detections. Water hardness is 358 mg/L (very hard), which can cause scale buildup in appliances and reduce soap effectiveness.

Contaminants detected in Cottage Grove water

Detection does not necessarily mean unsafe levels. See individual reports for concentrations and EPA limits.

Lead0.0023 / 0.015 mg/L
16% of EPA limit
Arsenic0.0015 / 0.01 mg/L
15% of EPA limit
Copper152 / 1300 ug/L
12% of EPA limit
Radium0.716 / 5 pCi/L
14% of EPA limit
Gross Alpha Radiation5.1 / 15 pCi/L
34% of EPA limit
7% of EPA limit
Fluoride0.81 / 4 mg/L
20% of EPA limit
Barium0.0126 / 2 mg/L
1% of EPA limit
Gross Beta2.5 / 50 pCi/L
5% of EPA limit
PFAS (tested — none detected)
Microplastics (not routinely tested)

Other cities in Dane County

Water quality reports for nearby Wisconsin communities.

Frequently asked questions

Is Cottage Grove, WI tap water safe to drink?
Cottage Grove tap water meets EPA legal standards (Maximum Contaminant Levels). However, 2 contaminants are present above independent health guidelines, which are often stricter than legal limits. 9 contaminants have been detected in the water supply, including Lead, Arsenic, Copper, Radium, Gross Alpha Radiation. View the detailed report for each water system to see specific levels and how they compare to both legal limits and health guidelines.
What contaminants are in Cottage Grove water?
Monitoring has detected 9 contaminants in Cottage Grove's water supply: Lead, Arsenic, Copper, Radium, Gross Alpha Radiation, Total Trihalomethanes, Fluoride, Barium, Gross Beta. 2 exceed health guidelines. See individual system reports for concentrations relative to EPA limits.
Does Cottage Grove water have PFAS?
Cottage Grove's water has been tested for PFAS compounds with no detections. Testing was conducted as part of the EPA's Unregulated Contaminant Monitoring Rule (UCMR5) program.
Is Cottage Grove water hard?
Yes. Cottage Grove water has a hardness of 358 mg/L (very hard). Hard water is not a health concern but can cause scale buildup in water heaters and appliances, reduce soap effectiveness, and leave mineral deposits. Water softeners or conditioning systems can address hardness.
Where does Cottage Grove get its drinking water?
Cottage Grove's drinking water comes from groundwater wells that draw from underground aquifers. The water is treated and tested according to Wisconsin DNR and EPA requirements before distribution. Cottage Grove is served by one water system: COTTAGE GROVE WATERWORKS.

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