{"schema_version":"1.2","pwsid":"WI4200469","system_name":"FOND DU LAC WATERWORKS","city":"FOND DU LAC","state":"WI","population_served":44303,"source_type":"GW","summary":"FOND DU LAC WATERWORKS serves approximately 44,303 people in FOND DU LAC, Wisconsin. Based on contaminant analyses from DNR, EPA ECHO, EPA UCMR5, 2 contaminants have been measured above federal EPA standards (MCL) and 4 exceed health-based guidelines. The most significant finding is Gross Alpha Radiation (excluding Radon and Uranium) at 41.3 pCi/L, which is 2.8x the EPA legal limit. Data is drawn from source-level compliance monitoring and covers 2016 through 2026. Results reflect conditions at the point of collection (wells, treatment plants), not necessarily at the tap.","data_period":{"start":"2016-09-30","end":"2026-04-01"},"contaminants_tested":134,"contaminants_detected":18,"exceedances":2,"guideline_exceedances":4,"contaminants":[{"name":"Chlorine (free)","code":"0700","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":1.19,"unit":"mg/L","sample_date":"2026-04-01","source":"DNR","source_scope":"source_monitoring","health_guideline_value":4,"health_guideline_source":"EPA MCLG","epa_mcl_value":4,"status":"below_limits","detection_limit":null},{"name":"Mercury (inorganic)","code":"1035","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.000029,"unit":"mg/L","sample_date":"2026-02-25","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.002,"health_guideline_source":"EPA 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(226+228)","code":"4010","cas_number":null,"group":"radionuclides","section":"legal_violation","measured_value":13.76,"unit":"pCi/L","sample_date":"2025-02-25","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0,"health_guideline_source":"EPA MCLG","epa_mcl_value":5,"status":"exceeds_legal_limit","detection_limit":null},{"name":"Gross Alpha Radiation (excluding Radon and 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(90th Percentile)","code":"PB90","cas_number":"7439-92-1","group":"lead_copper","section":"guideline_exceedance","measured_value":0.0079,"unit":"mg/L","sample_date":"2025-06-30","source":"EPA ECHO","source_scope":"federal_program","health_guideline_value":0.0002,"health_guideline_source":"OEHHA PHG","epa_mcl_value":null,"status":"exceeds_guideline","detection_limit":null},{"name":"Copper (90th Percentile)","code":"COPPER","cas_number":"7440-50-8","group":"lead_copper","section":"other_detected","measured_value":5.3,"unit":"ug/L","sample_date":"2025-12-04","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.3,"health_guideline_source":"OEHHA PHG","epa_mcl_value":null,"status":"below_limits","detection_limit":null},{"name":"Lithium","code":"lithium","cas_number":null,"group":"other","section":"pfas","measured_value":12,"unit":"ug/L","sample_date":"2023-10-09","source":"EPA 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Alpha","top_contaminant_code":"4000","max_value":39.6,"unit":"pCi/L","classification":"above_mcl","mcl_or_phg_value":15,"mcl_or_phg_unit":"pCi/L","validated_reason":null}],"has_only_historical_data":false,"pfas_hazard_index":null,"tthm_lraa":[{"monitoring_point":"system_wide","value":33.6,"unit":"ug/L","quarters_used":["2025Q2","2025Q3","2025Q4","2026Q1"],"sample_count":16,"mcl":80,"exceeds_mcl":false}],"haa5_lraa":[{"monitoring_point":"system_wide","value":7.49,"unit":"ug/L","quarters_used":["2025Q2","2025Q3","2025Q4","2026Q1"],"sample_count":16,"mcl":60,"exceeds_mcl":false}]}