Is Green Lake, WI Tap Water Safe to Drink?
Graded B-, with 27 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
74.5/100
waterverge.com Green Lake, WI — Water Quality Report
Green Lake's drinking water received a grade of B- (74.5 out of 100), indicating fair water quality. The city's 3 water systems serve approximately 1,152 residents using groundwater.
Lead levels were measured at 0.8 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 38 violations on record, including 5 health-based violations. 27 remain unresolved.
What to know about Green Lake's water
Green Lake ranks #326 out of 446 cities in Wisconsin for water quality, placing it below average in the state.
Green Lake relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
As a small community water system, Green Lake may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Green Lake, WI water safe to drink?
Green Lake's drinking water has significant quality concerns based on EPA testing data. With a grade of B- (74.5/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 3 water systems serve approximately 1,152 residents using groundwater (wells).
Recent water quality updates for Green Lake
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Green Lake's water quality assessment. Grade: B- (74.5/100).
1 health-based. Contaminants: Public Notice, LEAD AND COPPER RULE REVISIONS.
Contaminants: Lead and Copper Rule.
Contaminants: Consumer Confidence Rule.
Federal disaster declaration (FEMA DR-4402). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-3249). Hurricane event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Green Lake's water supply.
Well within EPA limits.
Violation history
Green Lake's water system has 38 total violations on record, including 5 health-based violations. 27 remain unresolved. 5 violations were issued in the last 5 years.
Flood & environmental risk
Green Lake County has experienced 3 federally declared disasters since 1973. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Wuerches Creek, Roy Creek, Green Lake Sw Inlet @ Ct Highwy K Nr Green Lake,Wi, White Creek, Silver Creek.
Where does Green Lake's water come from?
Green Lake's drinking water comes from groundwater (wells), supplied by 3 water systems serving approximately 1,152 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Wuerches Creek (river), Roy Creek (river), Green Lake Sw Inlet @ Ct Highwy K Nr Green Lake,Wi (river), White Creek (river), Silver Creek (river).
What Green Lake residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Green Lake's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Green Lake's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Green Lake
Industrial polluters nearby
Reported releases to surface water by facilities near Green Lake, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
SIGMA ENGINEERED SOLUTIONS MARKESAN, WI53946 | — | — | 8.6 mi |
DARLING INGREDIENTS INC BERLIN, WI54923 | — | — | 8.1 mi |
ALLIANCE LAUNDRY SYSTEMS LLC STANTON PLANT RIPON, WI54971 | — | — | 6.5 mi |
ALLIANCE LAUNDRY SYSTEMS LLC RIPON, WI54971 | — | — | 6.2 mi |
SENECA FOODS CORP RIPON, WI54971 | — | — | 6.7 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Superfund sites within 10 miles of Green Lake
Superfund sites nearby
Federally tracked hazardous-waste sites on the EPA National Priorities List. Proximity does not necessarily indicate tap-water contamination — the connection depends on hydrology and treatment.
- RIPON CITY LANDFILL4.6 mi
Source: EPA Superfund National Priorities List
Flood & disaster history
Green Lake County has experienced 3 federally declared disasters since 1973. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 0.8 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Green Lake compares by contaminant
Explore where Green Lake ranks among all Wisconsin cities for specific contaminants.
Water source & infrastructure
Where Green Lake's water comes from
Green Lake's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by local government ownership and serves approximately 1,152 people through 3 water systems.
Water bodies near Green Lake
Green Lake is located near 5 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Green Lake
| System Name | PWSID | Population | Source |
|---|---|---|---|
| GREEN LAKE WATERWORKS | WI4240217 | 1,002 | GW |
| LAMPLIGHTER MHC LLC | WI4240221 | 80 | GW |
| GREEN LAKE MHP | WI4240223 | 70 | GW |
How Green Lake compares
Full Wisconsin rankings →Green Lake's score of 74.5/100 is above the average of 65/100 among major Wisconsin cities. It outscores 6 of 10 nearby cities.
Nearby cities
View Wisconsin rankings →About Green Lake, WI
Wikipedia →Green Lake is a city in, and the county seat of, Green Lake County, Wisconsin, United States. The city had a population of 1,001 in the 2020 census. It is located on the north side of Green Lake. The Town of Green Lake is located on the south side of Big Green Lake, opposite the city.
Learn more about your water
Guides and resources related to Green Lake's water quality findings.
Explore water quality across Green Lake
Frequently asked questions
Is Green Lake, WI tap water safe to drink?
Green Lake's water quality earned a grade of B- (74.5/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #326 out of 446 cities tested in Wisconsin.
What contaminants are in Green Lake's water?
Lead was measured at 0.8 ppb (90th percentile). 38 violations are on record.
How is Green Lake's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Green Lake?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Green Lake's water come from?
Green Lake's water is sourced from Groundwater. The city has 3 water systems serving approximately 1,152 residents.
What health violations has Green Lake's water system had?
Green Lake has 5 health-based violations on record. The most recent violation was recorded in October 2024. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 27 violations remain unresolved.
Is Green Lake's groundwater at risk of contamination?
Green Lake uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 38 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Green Lake's water compare to other cities?
Green Lake ranks #326 out of 446 cities in Wisconsin (better than 27% of state cities) and #9843 out of 15744 cities nationally (38th percentile). The grade of B- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.