{"schema_version":"1.2","pwsid":"WI2410172","system_name":"OAK CREEK WATERWORKS","city":"Oak Creek","state":"WI","population_served":32104,"source_type":"SW","summary":"OAK CREEK WATERWORKS serves approximately 32,104 people in Oak Creek, Wisconsin. Based on contaminant analyses from DNR, WQP, 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 1 contaminant. 2 contaminants exceed health-based guidelines. The most significant finding is Lead (90th Percentile) at 0.002 mg/L, which is 10x the health guideline. Data is drawn from source-level compliance monitoring and covers 1995 through 2026. Results reflect conditions at the point of collection (wells, treatment plants), not necessarily at the tap.","data_period":{"start":"1995-06-19","end":"2026-04-01"},"contaminants_tested":135,"contaminants_detected":24,"exceedances":0,"guideline_exceedances":2,"contaminants":[{"name":"Chlorine (free)","code":"0700","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":1.69,"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":"Chlorine (total residual)","code":"0700_TOTAL","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":1.83,"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":"Fluoride (natural)","code":"FLUORIDE","cas_number":"16984-48-8","group":"inorganics","section":"other_detected","measured_value":0.671,"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":"Haloacetic Acids (HAA5)","code":"2456","cas_number":null,"group":"dbps","section":"other_detected","measured_value":10.88,"unit":"ug/L","sample_date":"2026-01-06","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":22.94,"unit":"ug/L","sample_date":"2026-01-06","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":0.53,"unit":"ug/L","sample_date":"2010-07-15","source":"WQP","source_scope":"regional_groundwater","health_guideline_value":0.1,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.1,"status":"below_limits","detection_limit":null},{"name":"Mercury (inorganic)","code":"1035","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.00007,"unit":"mg/L","sample_date":"2024-03-05","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":"Arsenic","code":"ARSENIC","cas_number":"7440-38-2","group":"inorganics","section":"guideline_exceedance","measured_value":0.00047,"unit":"mg/L","sample_date":"2021-03-09","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":"Nickel","code":"1036","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.00085,"unit":"mg/L","sample_date":"2025-04-08","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":"Selenium","code":"1045","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.0017,"unit":"mg/L","sample_date":"2025-04-08","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":"Barium","code":"BARIUM","cas_number":"7440-39-3","group":"inorganics","section":"other_detected","measured_value":0.02,"unit":"mg/L","sample_date":"2025-04-08","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":"Nitrate (as N)","code":"NITRATE","cas_number":"14797-55-8","group":"inorganics","section":"other_detected","measured_value":0.41,"unit":"mg/L","sample_date":"2025-04-08","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":"Chloroethane","code":"CHLOROETHANE","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.15,"unit":"ug/L","sample_date":"2025-01-07","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Atrazine","code":"2050","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.032,"unit":"ug/L","sample_date":"2023-07-11","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":0.0071,"unit":"ug/L","sample_date":"2023-04-10","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":"PFHpA (Perfluoroheptanoic Acid)","code":"PFHPA","cas_number":null,"group":"pfas","section":"other_detected","measured_value":0.9,"unit":"ng/L","sample_date":"2023-04-10","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Chloramines","code":"0600","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":0.19,"unit":"mg/L","sample_date":"2021-09-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":4,"health_guideline_source":"EPA 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Not a current MCL."},"well_counts":{"active":0,"retired":3,"facilities_synced_at":"2026-04-11T13:48:07.246Z"},"historical_wells":[],"has_only_historical_data":false,"pfas_hazard_index":{"value":0.0882,"compounds_used":["PFHXS","PFBS"],"is_partial":true,"threshold":1,"components":[{"code":"PFHXS","value_ng_l":0.88,"hbwc_ng_l":10,"ratio":0.088},{"code":"PFBS","value_ng_l":0.39,"hbwc_ng_l":2000,"ratio":0.0002}]},"tthm_lraa":[{"monitoring_point":"system_wide","value":22.94,"unit":"ug/L","quarters_used":["2025Q2","2025Q3","2025Q4","2026Q1"],"sample_count":8,"mcl":80,"exceeds_mcl":false}],"haa5_lraa":[{"monitoring_point":"system_wide","value":10.88,"unit":"ug/L","quarters_used":["2025Q2","2025Q3","2025Q4","2026Q1"],"sample_count":8,"mcl":60,"exceeds_mcl":false}]}