{"schema_version":"1.2","pwsid":"WI1130224","system_name":"MADISON WATER UTILITY","city":"MADISON","state":"WI","population_served":272000,"source_type":"GW","summary":"MADISON WATER UTILITY serves approximately 272,000 people in MADISON, Wisconsin. Based on contaminant analyses from DNR, WQP, EPA ECHO, EPA UCMR5, 0 contaminants have been measured above federal EPA standards (MCL) and 5 exceed health-based guidelines. The most significant finding is Arsenic at 0.0067 mg/L, which is 1675x the health guideline. Data is drawn from source-level compliance monitoring and covers 2014 through 2026. Results reflect conditions at the point of collection (wells, treatment plants), not necessarily at the tap.","data_period":{"start":"2014-07-09","end":"2026-09-30"},"contaminants_tested":179,"contaminants_detected":48,"exceedances":0,"guideline_exceedances":5,"contaminants":[{"name":"Chlorine (free)","code":"0700","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":0.43,"unit":"mg/L","sample_date":"2026-09-30","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":1.34,"unit":"mg/L","sample_date":"2026-09-28","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":"PFPeA (Perfluoropentanoic Acid)","code":"PFPEA","cas_number":null,"group":"pfas","section":"other_detected","measured_value":3.6,"unit":"ng/L","sample_date":"2026-09-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"6:2 FTS (6:2 Fluorotelomer Sulfonate)","code":"6_2_FTSA","cas_number":null,"group":"pfas","section":"other_detected","measured_value":1.2,"unit":"ng/L","sample_date":"2026-09-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"PFHpA (Perfluoroheptanoic Acid)","code":"PFHPA","cas_number":null,"group":"pfas","section":"other_detected","measured_value":1.5,"unit":"ng/L","sample_date":"2026-09-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Fluoride (natural)","code":"FLUORIDE","cas_number":"16984-48-8","group":"inorganics","section":"other_detected","measured_value":0.65,"unit":"mg/L","sample_date":"2026-09-10","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":"Uranium","code":"4006","cas_number":"7440-61-1","group":"radionuclides","section":"guideline_exceedance","measured_value":0.66,"unit":"ug/L","sample_date":"2026-09-01","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":"Combined Radium (226+228)","code":"4010","cas_number":null,"group":"radionuclides","section":"other_detected","measured_value":4.1,"unit":"pCi/L","sample_date":"2026-09-01","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0,"health_guideline_source":"EPA MCLG","epa_mcl_value":5,"status":"approaching","detection_limit":null},{"name":"Gross Alpha Radiation (excluding Radon and Uranium)","code":"4000_EXCL","cas_number":null,"group":"radionuclides","section":"other_detected","measured_value":10.7,"unit":"pCi/L","sample_date":"2026-09-01","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":"PFPeS (Perfluoropentane Sulfonate)","code":"PFPES","cas_number":null,"group":"pfas","section":"other_detected","measured_value":0.71,"unit":"ng/L","sample_date":"2023-03-27","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Chloromethane","code":"CHLOROMETHANE","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.45,"unit":"ug/L","sample_date":"2021-05-26","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Trichlorofluoromethane","code":"TRICHLOROFLUOROMETHANE","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.41,"unit":"ug/L","sample_date":"2026-07-14","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Styrene","code":"2955","cas_number":null,"group":"other","section":"other_detected","measured_value":0.43,"unit":"ug/L","sample_date":"2025-09-03","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Trichloroethylene (TCE)","code":"2984","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.26,"unit":"ug/L","sample_date":"2026-07-14","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.0017,"health_guideline_source":"OEHHA PHG","epa_mcl_value":0.005,"status":"below_limits","detection_limit":null},{"name":"1,1-Dichloroethane","code":"2968","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.11,"unit":"ug/L","sample_date":"2023-02-20","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Trichlorotrifluoroethane Freon","code":"TRICHLOROTRIFLUOROETHANE_FREON","cas_number":null,"group":"other","section":"other_detected","measured_value":0.54,"unit":"ug/L","sample_date":"2021-01-19","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Benzene","code":"2990","cas_number":null,"group":"vocs","section":"guideline_exceedance","measured_value":0.39,"unit":"ug/L","sample_date":"2025-11-24","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.00015,"health_guideline_source":"OEHHA PHG","epa_mcl_value":0.005,"status":"exceeds_guideline","detection_limit":null},{"name":"1,1-Dichloroethylene","code":"2010","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.18,"unit":"ug/L","sample_date":"2024-07-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.007,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.007,"status":"below_limits","detection_limit":null},{"name":"cis-1,2-Dichloroethylene","code":"2943","cas_number":"156-59-2","group":"vocs","section":"other_detected","measured_value":0.25,"unit":"ug/L","sample_date":"2026-07-14","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.07,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.07,"status":"below_limits","detection_limit":null},{"name":"Tetrachloroethylene (PCE)","code":"2987","cas_number":null,"group":"vocs","section":"guideline_exceedance","measured_value":1.3,"unit":"ug/L","sample_date":"2026-07-14","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.00006,"health_guideline_source":"OEHHA PHG","epa_mcl_value":0.005,"status":"exceeds_guideline","detection_limit":null},{"name":"Total Xylenes","code":"2969","cas_number":"1330-20-7","group":"organic","section":"other_detected","measured_value":0.82,"unit":"ug/L","sample_date":"2026-07-14","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.5,"health_guideline_source":"WHO Guideline","epa_mcl_value":10,"status":"below_limits","detection_limit":null},{"name":"Ethylbenzene","code":"2966","cas_number":null,"group":"other","section":"other_detected","measured_value":0.12,"unit":"ug/L","sample_date":"2026-07-14","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"O Xylene","code":"O_XYLENE","cas_number":null,"group":"other","section":"other_detected","measured_value":0.33,"unit":"ug/L","sample_date":"2026-07-14","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"P Xylene","code":"P_XYLENE","cas_number":null,"group":"other","section":"other_detected","measured_value":0.49,"unit":"ug/L","sample_date":"2026-07-14","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Metolachlor","code":"2034","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.012,"unit":"ug/L","sample_date":"2023-07-17","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":"Atrazine","code":"2050","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.044,"unit":"ug/L","sample_date":"2026-08-03","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":"Haloacetic Acids (HAA5)","code":"2456","cas_number":null,"group":"dbps","section":"other_detected","measured_value":1.32,"unit":"ug/L","sample_date":"2026-07-20","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":3.61,"unit":"ug/L","sample_date":"2026-07-20","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":"Chromium (total)","code":"CHROMIUM","cas_number":"7440-47-3","group":"inorganics","section":"other_detected","measured_value":0.0016,"unit":"mg/L","sample_date":"2026-06-24","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.1,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.1,"status":"below_limits","detection_limit":null},{"name":"Barium","code":"BARIUM","cas_number":"7440-39-3","group":"inorganics","section":"other_detected","measured_value":0.0133,"unit":"mg/L","sample_date":"2026-06-24","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":"Thallium","code":"1038","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.00025,"unit":"mg/L","sample_date":"2026-06-23","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.0005,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.002,"status":"below_limits","detection_limit":null},{"name":"Selenium","code":"1045","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.0012,"unit":"mg/L","sample_date":"2026-06-23","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.05,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.05,"status":"below_limits","detection_limit":null},{"name":"Nitrate (as N)","code":"NITRATE","cas_number":"14797-55-8","group":"inorganics","section":"other_detected","measured_value":2.71,"unit":"mg/L","sample_date":"2026-06-23","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":"Nickel","code":"1036","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.0018,"unit":"mg/L","sample_date":"2026-06-22","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":"Silver","code":"SILVER","cas_number":"7440-22-4","group":"metal","section":"other_detected","measured_value":0.00016,"unit":"mg/L","sample_date":"2025-10-08","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"below_limits","detection_limit":null},{"name":"Beryllium","code":"1006","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.000198,"unit":"mg/L","sample_date":"2021-05-26","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.004,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.004,"status":"below_limits","detection_limit":null},{"name":"Arsenic","code":"ARSENIC","cas_number":"7440-38-2","group":"inorganics","section":"guideline_exceedance","measured_value":0.0067,"unit":"mg/L","sample_date":"2025-06-09","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.000004,"health_guideline_source":"OEHHA PHG","epa_mcl_value":0.01,"status":"exceeds_guideline","detection_limit":null},{"name":"Nitrite (as N)","code":"1041","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.0128,"unit":"mg/L","sample_date":"2025-05-06","source":"DNR","source_scope":"source_monitoring","health_guideline_value":1,"health_guideline_source":"EPA MCLG","epa_mcl_value":1,"status":"below_limits","detection_limit":null},{"name":"Radon","code":"RADON","cas_number":"10043-92-2","group":"radionuclide","section":"other_detected","measured_value":223,"unit":"pCi/L","sample_date":"2021-05-26","source":"DNR","source_scope":"source_monitoring","health_guideline_value":300,"health_guideline_source":"EPA proposed MCL (1999, never finalized)","epa_mcl_value":null,"status":"below_limits","detection_limit":null},{"name":"Turbidity","code":"TURBIDITY","cas_number":null,"group":"other","section":"other_detected","measured_value":0.15,"unit":"NTU","sample_date":"2026-06-01","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Lead (90th Percentile)","code":"PB90","cas_number":"7439-92-1","group":"lead_copper","section":"guideline_exceedance","measured_value":0.0018,"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":110,"unit":"ug/L","sample_date":"2026-09-04","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":"PFBS (Perfluorobutane Sulfonate)","code":"PFBS","cas_number":"375-73-5","group":"pfas","section":"pfas","measured_value":1.5,"unit":"ng/L","sample_date":"2026-09-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"PFHxS (Perfluorohexane Sulfonate)","code":"PFHXS","cas_number":"355-46-4","group":"pfas","section":"pfas","measured_value":0.55,"unit":"ng/L","sample_date":"2026-09-21","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},{"name":"PFOS (Perfluorooctane Sulfonate)","code":"PFOS","cas_number":"1763-23-1","group":"pfas","section":"pfas","measured_value":2,"unit":"ng/L","sample_date":"2026-09-15","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":"PFOA (Perfluorooctanoic Acid)","code":"PFOA","cas_number":"335-67-1","group":"pfas","section":"pfas","measured_value":2,"unit":"ng/L","sample_date":"2026-09-15","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":"PFBA (Perfluorobutanoic Acid)","code":"PFBA","cas_number":null,"group":"pfas","section":"pfas","measured_value":45,"unit":"ng/L","sample_date":"2026-09-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"PFHxA (Perfluorohexanoic Acid)","code":"PFHXA","cas_number":"307-24-4","group":"pfas","section":"pfas","measured_value":2.1,"unit":"ng/L","sample_date":"2026-09-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null}],"sources":[{"name":"DNR","url":"https://apps.dnr.wi.gov/dwsportalpub"},{"name":"WQP","url":"https://www.waterqualitydata.us/"},{"name":"EPA ECHO","url":"https://echo.epa.gov/"},{"name":"EPA UCMR5","url":"https://www.epa.gov/dwucmr/fifth-unregulated-contaminant-monitoring-rule"}],"pfas_combined_display":{"value":3.3,"unit":"ng/L","sample_date":"2026-09-15","note":"Legacy 2016 EPA Health Advisory combined PFOA+PFOS metric. Not a current MCL."},"well_counts":{"active":20,"retired":10,"facilities_synced_at":"2026-10-15T05:00:54.057Z"},"historical_wells":[],"has_only_historical_data":false,"pfas_hazard_index":{"value":0.0558,"compounds_used":["PFHXS","PFBS"],"is_partial":true,"threshold":1,"components":[{"code":"PFHXS","value_ng_l":0.55,"hbwc_ng_l":10,"ratio":0.055},{"code":"PFBS","value_ng_l":1.5,"hbwc_ng_l":2000,"ratio":0.0008}]},"tthm_lraa":[{"monitoring_point":"system_wide","value":3.61,"unit":"ug/L","quarters_used":["2025Q4","2026Q1","2026Q2","2026Q3"],"sample_count":10,"mcl":80,"exceeds_mcl":false}],"haa5_lraa":[{"monitoring_point":"system_wide","value":1.32,"unit":"ug/L","quarters_used":["2025Q3","2025Q4","2026Q1","2026Q3"],"sample_count":8,"mcl":60,"exceeds_mcl":false}]}