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Water Quality Report

Onalaska, WI

La Crosse County · 18,000 residents · 1 water system

17

Contaminants detected

5

PFAS compounds

366

Hardness (mg/L)

0

Above legal limits

3

Above health guidelines

Onalaska drinking water comes from groundwater wells. Based on the most recent monitoring data, 17 contaminants have been detected in the water supply, including Lead, Nitrate, Arsenic, Copper, and 13 others. PFAS compounds have been detected at trace levels in Onalaska water. Water hardness is 366 mg/L (very hard), which can cause scale buildup in appliances and reduce soap effectiveness.

Contaminants detected in Onalaska water

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

Lead0 / 0.015 mg/L
0% of EPA limit
Nitrate5.7 / 10 mg/L
57% of EPA limit
Arsenic0.002 / 0.01 mg/L
20% of EPA limit
Copper556 / 1300 ug/L
43% of EPA limit
Radium0.28 / 5 pCi/L
6% of EPA limit
Uranium0.62 / 30 ug/L
2% of EPA limit
Total Trihalomethanes18.6 / 80 ug/L
23% of EPA limit
Haloacetic Acids (HAA5)22 / 60 ug/L
37% of EPA limit
Selenium0.002 / 0.05 mg/L
4% of EPA limit
Fluoride0.69 / 4 mg/L
17% of EPA limit
PFHpA (Perfluoroheptanoic Acid)1.1 ng/L
UnregulatedPFAS
Thallium0.0002 / 0.002 mg/L
10% of EPA limit
Barium0.0931 / 2 mg/L
5% of EPA limit
Antimony0.001 / 0.006 mg/L
17% of EPA limit
Beryllium0.0001 / 0.004 mg/L
3% of EPA limit
Orthophosphate0.432 ug/L
Unregulated
Phosphorus Total0.523 ug/L
Unregulated
PFAS (5 compounds detected)
Microplastics (not routinely tested)

Water systems serving Onalaska

ONALASKA WATERWORKS

18,000 servedGroundwater17 contaminants3 above guidelines
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Other cities in La Crosse County

Water quality reports for nearby Wisconsin communities.

BangorHolmenLa CrosseLacrosseMindoroRocklandWest Salem

Frequently asked questions

Is Onalaska, WI tap water safe to drink?
Onalaska tap water meets EPA legal standards (Maximum Contaminant Levels). However, 3 contaminants are present above independent health guidelines, which are often stricter than legal limits. 17 contaminants have been detected in the water supply, including Lead, Nitrate, Arsenic, Copper, Radium. 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 Onalaska water?
Monitoring has detected 17 contaminants in Onalaska's water supply: Lead, Nitrate, Arsenic, Copper, Radium, Uranium, Total Trihalomethanes, Haloacetic Acids (HAA5), Selenium, Fluoride, PFHpA (Perfluoroheptanoic Acid), Thallium, Barium, Antimony, Beryllium, Orthophosphate, Phosphorus Total. Additionally, 5 PFAS compounds have been detected at trace levels. 3 exceed health guidelines. See individual system reports for concentrations relative to EPA limits.
Does Onalaska water have PFAS?
Yes. 5 PFAS compounds have been detected in Onalaska's water supply at trace levels. PFAS are sometimes called "forever chemicals" because they do not break down in the environment. The EPA has set Maximum Contaminant Levels for several PFAS compounds. View the detailed report for specific concentrations.
Is Onalaska water hard?
Yes. Onalaska water has a hardness of 366 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 Onalaska get its drinking water?
Onalaska'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. Onalaska is served by one water system: ONALASKA WATERWORKS.

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