{"schema_version":"1.2","pwsid":"WI6420254","system_name":"TOMAH WATERWORKS","city":"TOMAH","state":"WI","population_served":9192,"source_type":"GW","summary":"TOMAH WATERWORKS serves approximately 9,192 people in TOMAH, Wisconsin. Based on contaminant analyses from DNR, EPA ECHO, EPA UCMR5, the most recent monitoring readings are within federal EPA standards (MCL), but this system has active MCL violations on record for 2 contaminants. 1 contaminant exceeds health-based guidelines. The most significant finding is Copper (90th Percentile) at 1210 ug/L, which is 4x the health guideline. 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":"2026-03-24"},"contaminants_tested":109,"contaminants_detected":27,"exceedances":0,"guideline_exceedances":1,"contaminants":[{"name":"Chlorine (free)","code":"0700","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":1.17,"unit":"mg/L","sample_date":"2026-03-24","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":"Styrene","code":"2955","cas_number":null,"group":"other","section":"other_detected","measured_value":0.99,"unit":"ug/L","sample_date":"2023-08-22","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Selenium","code":"1045","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.001,"unit":"mg/L","sample_date":"2023-03-06","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":"Fluoride (natural)","code":"FLUORIDE","cas_number":"16984-48-8","group":"inorganics","section":"other_detected","measured_value":0.11,"unit":"mg/L","sample_date":"2026-03-10","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":"Thallium","code":"1038","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.0002,"unit":"mg/L","sample_date":"2026-03-10","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":"Mercury (inorganic)","code":"1035","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.0001,"unit":"mg/L","sample_date":"2023-03-06","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.002,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.002,"status":"below_limits","detection_limit":null},{"name":"Barium","code":"BARIUM","cas_number":"7440-39-3","group":"inorganics","section":"other_detected","measured_value":0.0508,"unit":"mg/L","sample_date":"2026-03-10","source":"DNR","source_scope":"source_monitoring","health_guideline_value":1,"health_guideline_source":"OEHHA PHG 2003 (hypertension 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N)","code":"NITRATE","cas_number":"14797-55-8","group":"inorganics","section":"other_detected","measured_value":6.3,"unit":"mg/L","sample_date":"2026-03-10","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":"Total Trihalomethanes (TTHMs)","code":"2950","cas_number":null,"group":"dbps","section":"other_detected","measured_value":5.49,"unit":"ug/L","sample_date":"2025-07-22","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":"Haloacetic Acids (HAA5)","code":"2456","cas_number":null,"group":"dbps","section":"other_detected","measured_value":10.88,"unit":"ug/L","sample_date":"2025-07-22","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":"Uranium","code":"4006","cas_number":"7440-61-1","group":"radionuclides","section":"other_detected","measured_value":0.019,"unit":"ug/L","sample_date":"2025-06-02","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.0005,"health_guideline_source":"OEHHA PHG","epa_mcl_value":0.03,"status":"below_limits","detection_limit":null},{"name":"Combined Radium (226+228)","code":"4010","cas_number":null,"group":"radionuclides","section":"other_detected","measured_value":3.805,"unit":"pCi/L","sample_date":"2025-06-02","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0,"health_guideline_source":"EPA MCLG","epa_mcl_value":5,"status":"below_limits","detection_limit":null},{"name":"Gross Alpha Radiation (excluding Radon and Uranium)","code":"4000_EXCL","cas_number":null,"group":"radionuclides","section":"other_detected","measured_value":2.975,"unit":"pCi/L","sample_date":"2025-06-02","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":"Chlorine (total residual)","code":"0700_TOTAL","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":1.03,"unit":"mg/L","sample_date":"2025-02-26","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":"PFHpA (Perfluoroheptanoic 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PHG","epa_mcl_value":null,"status":"below_limits","detection_limit":null},{"name":"Copper (90th Percentile)","code":"COPPER","cas_number":"7440-50-8","group":"lead_copper","section":"guideline_exceedance","measured_value":1210,"unit":"ug/L","sample_date":"2023-07-14","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.3,"health_guideline_source":"OEHHA PHG","epa_mcl_value":null,"status":"exceeds_guideline","detection_limit":null},{"name":"Pfpea","code":"PFPeA","cas_number":null,"group":"other","section":"pfas","measured_value":0.0047,"unit":"ug/L","sample_date":"2023-09-25","source":"EPA UCMR5","source_scope":"federal_program","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":0.003},{"name":"Pfhxa","code":"PFHxA","cas_number":null,"group":"other","section":"pfas","measured_value":0.0037,"unit":"ug/L","sample_date":"2023-09-25","source":"EPA UCMR5","source_scope":"federal_program","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":0.003},{"name":"PFHxS (Perfluorohexane Sulfonate)","code":"PFHXS","cas_number":"355-46-4","group":"pfas","section":"pfas","measured_value":0.0057,"unit":"ug/L","sample_date":"2023-09-25","source":"EPA UCMR5","source_scope":"federal_program","health_guideline_value":0.01,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.01,"status":"below_limits","detection_limit":0.003},{"name":"PFBS (Perfluorobutane Sulfonate)","code":"PFBS","cas_number":"375-73-5","group":"pfas","section":"pfas","measured_value":1,"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":"PFOS (Perfluorooctane Sulfonate)","code":"PFOS","cas_number":"1763-23-1","group":"pfas","section":"pfas","measured_value":0.84,"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":"PFOA (Perfluorooctanoic Acid)","code":"PFOA","cas_number":"335-67-1","group":"pfas","section":"pfas","measured_value":1.2,"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":"PFHxA (Perfluorohexanoic Acid)","code":"PFHXA","cas_number":"307-24-4","group":"pfas","section":"pfas","measured_value":3.4,"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}],"sources":[{"name":"DNR","url":"https://apps.dnr.wi.gov/dwsportalpub"},{"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":2.04,"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":4,"retired":10,"facilities_synced_at":"2026-04-11T13:48:07.246Z"},"historical_wells":[{"state_facility_id":"14","facility_name":"YO934","deactivation_date":"2026-02-24","top_contaminant":"Nitrate (as N)","top_contaminant_code":"NITRATE","max_value":14.4,"unit":"mg/L","classification":"above_mcl","mcl_or_phg_value":10,"mcl_or_phg_unit":"mg/L","validated_reason":null}],"has_only_historical_data":false,"pfas_hazard_index":{"value":0.5705,"compounds_used":["PFHXS","PFBS"],"is_partial":true,"threshold":1,"components":[{"code":"PFHXS","value_ng_l":5.7,"hbwc_ng_l":10,"ratio":0.57},{"code":"PFBS","value_ng_l":1,"hbwc_ng_l":2000,"ratio":0.0005}]},"tthm_lraa":[{"monitoring_point":"system_wide","value":5.49,"unit":"ug/L","quarters_used":["2022Q3","2023Q3","2024Q3","2025Q3"],"sample_count":4,"mcl":80,"exceeds_mcl":false}],"haa5_lraa":[{"monitoring_point":"system_wide","value":10.88,"unit":"ug/L","quarters_used":["2022Q3","2023Q3","2024Q3","2025Q3"],"sample_count":4,"mcl":60,"exceeds_mcl":false}]}