{"schema_version":"1.2","pwsid":"WI7370151","system_name":"MARATHON CITY WATERWORKS","city":"MARATHON CITY","state":"WI","population_served":1695,"source_type":"GW","summary":"MARATHON CITY WATERWORKS serves approximately 1,695 people in MARATHON CITY, Wisconsin. Based on contaminant analyses from DNR, EPA ECHO, 1 contaminant has been measured above federal EPA standards (MCL) and 3 exceed health-based guidelines. The most significant finding is Combined Radium (226+228) at 7.21 pCi/L, which is 1.4x the EPA legal limit. Data is drawn from source-level compliance monitoring and covers 2017 through 2026. Results reflect conditions at the point of collection (wells, treatment plants), not necessarily at the tap.","data_period":{"start":"2017-09-30","end":"2026-09-23"},"contaminants_tested":88,"contaminants_detected":19,"exceedances":1,"guideline_exceedances":3,"contaminants":[{"name":"Chlorine (free)","code":"0700","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":0.14,"unit":"mg/L","sample_date":"2026-09-23","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":"Chlorine (total residual)","code":"0700_TOTAL","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":1.11,"unit":"mg/L","sample_date":"2026-09-14","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":"Fluoride (natural)","code":"FLUORIDE","cas_number":"16984-48-8","group":"inorganics","section":"other_detected","measured_value":0.56,"unit":"mg/L","sample_date":"2026-09-14","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":"Haloacetic Acids (HAA5)","code":"2456","cas_number":null,"group":"dbps","section":"other_detected","measured_value":8.13,"unit":"ug/L","sample_date":"2026-07-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.0001,"health_guideline_source":"EWG Health Guideline","epa_mcl_value":0.06,"status":"below_limits","detection_limit":null},{"name":"Total Trihalomethanes (TTHMs)","code":"2950","cas_number":null,"group":"dbps","section":"other_detected","measured_value":35.74,"unit":"ug/L","sample_date":"2026-07-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.00015,"health_guideline_source":"EWG Health Guideline","epa_mcl_value":0.08,"status":"below_limits","detection_limit":null},{"name":"Nickel","code":"1036","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.0016,"unit":"mg/L","sample_date":"2026-06-09","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.012,"health_guideline_source":"OEHHA PHG","epa_mcl_value":null,"status":"below_limits","detection_limit":null},{"name":"Atrazine","code":"2050","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.02,"unit":"ug/L","sample_date":"2026-06-09","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.00015,"health_guideline_source":"OEHHA PHG 1999","epa_mcl_value":0.003,"status":"below_limits","detection_limit":null},{"name":"Metolachlor","code":"2034","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.025,"unit":"ug/L","sample_date":"2026-06-09","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.01,"health_guideline_source":"WHO Guideline","epa_mcl_value":null,"status":"below_limits","detection_limit":null},{"name":"Barium","code":"BARIUM","cas_number":"7440-39-3","group":"inorganics","section":"other_detected","measured_value":0.05,"unit":"mg/L","sample_date":"2026-06-09","source":"DNR","source_scope":"source_monitoring","health_guideline_value":1,"health_guideline_source":"OEHHA PHG 2003 (hypertension endpoint)","epa_mcl_value":2,"status":"below_limits","detection_limit":null},{"name":"Uranium","code":"4006","cas_number":"7440-61-1","group":"radionuclides","section":"guideline_exceedance","measured_value":0.576,"unit":"ug/L","sample_date":"2026-06-09","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.0005,"health_guideline_source":"OEHHA PHG","epa_mcl_value":0.03,"status":"exceeds_guideline","detection_limit":null},{"name":"Nitrate (as N)","code":"NITRATE","cas_number":"14797-55-8","group":"inorganics","section":"other_detected","measured_value":2.7,"unit":"mg/L","sample_date":"2026-06-09","source":"DNR","source_scope":"source_monitoring","health_guideline_value":10,"health_guideline_source":"EPA MCLG","epa_mcl_value":10,"status":"below_limits","detection_limit":null},{"name":"Combined Radium (226+228)","code":"4010","cas_number":null,"group":"radionuclides","section":"legal_violation","measured_value":7.21,"unit":"pCi/L","sample_date":"2026-06-09","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 Uranium)","code":"4000_EXCL","cas_number":null,"group":"radionuclides","section":"other_detected","measured_value":8.59,"unit":"pCi/L","sample_date":"2026-06-09","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":15,"status":"below_limits","detection_limit":null},{"name":"Lead (90th Percentile)","code":"PB90","cas_number":"7439-92-1","group":"lead_copper","section":"guideline_exceedance","measured_value":0.00036,"unit":"mg/L","sample_date":"2023-09-30","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":37,"unit":"ug/L","sample_date":"2026-07-14","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":"PFBS (Perfluorobutane Sulfonate)","code":"PFBS","cas_number":"375-73-5","group":"pfas","section":"pfas","measured_value":0.46,"unit":"ng/L","sample_date":"2023-04-18","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"PFOA (Perfluorooctanoic Acid)","code":"PFOA","cas_number":"335-67-1","group":"pfas","section":"pfas","measured_value":0.83,"unit":"ng/L","sample_date":"2023-04-18","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.004,"status":"below_limits","detection_limit":null},{"name":"PFOS (Perfluorooctane Sulfonate)","code":"PFOS","cas_number":"1763-23-1","group":"pfas","section":"pfas","measured_value":0.91,"unit":"ng/L","sample_date":"2023-04-18","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.004,"status":"below_limits","detection_limit":null},{"name":"PFHxS (Perfluorohexane Sulfonate)","code":"PFHXS","cas_number":"355-46-4","group":"pfas","section":"pfas","measured_value":1.4,"unit":"ng/L","sample_date":"2023-04-18","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.01,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.01,"status":"below_limits","detection_limit":null}],"sources":[{"name":"DNR","url":"https://apps.dnr.wi.gov/dwsportalpub"},{"name":"EPA ECHO","url":"https://echo.epa.gov/"}],"pfas_combined_display":{"value":1.74,"unit":"ng/L","sample_date":"2023-04-18","note":"Legacy 2016 EPA Health Advisory combined PFOA+PFOS metric. Not a current MCL."},"well_counts":{"active":3,"retired":1,"facilities_synced_at":"2026-10-15T05:00:54.057Z"},"historical_wells":[],"has_only_historical_data":false,"pfas_hazard_index":{"value":0.1402,"compounds_used":["PFHXS","PFBS"],"is_partial":true,"threshold":1,"components":[{"code":"PFHXS","value_ng_l":1.4,"hbwc_ng_l":10,"ratio":0.14},{"code":"PFBS","value_ng_l":0.46,"hbwc_ng_l":2000,"ratio":0.0002}]},"tthm_lraa":[{"monitoring_point":"system_wide","value":35.74,"unit":"ug/L","quarters_used":["2025Q4","2026Q1","2026Q2","2026Q3"],"sample_count":8,"mcl":80,"exceeds_mcl":false}],"haa5_lraa":[{"monitoring_point":"system_wide","value":8.13,"unit":"ug/L","quarters_used":["2025Q4","2026Q1","2026Q2","2026Q3"],"sample_count":8,"mcl":60,"exceeds_mcl":false}]}