{"schema_version":"1.2","pwsid":"WI6480240","system_name":"MAIDEN ROCK WATER UTILITY","city":"Maiden Rock","state":"WI","population_served":118,"source_type":"GW","summary":"MAIDEN ROCK WATER UTILITY serves approximately 118 people in Maiden Rock, Wisconsin. Based on contaminant analyses from DNR, WQP, EPA ECHO, 0 contaminants have been measured above federal EPA standards (MCL) and 1 exceeds health-based guidelines. The most significant finding is Lead (90th Percentile) at 0.00039 mg/L, which is 2x the health guideline. Data is drawn from source-level compliance monitoring and covers 1996 through 2026. Results reflect conditions at the point of collection (wells, treatment plants), not necessarily at the tap.","data_period":{"start":"1996-07-31","end":"2026-04-02"},"contaminants_tested":136,"contaminants_detected":17,"exceedances":0,"guideline_exceedances":1,"contaminants":[{"name":"Chloramines","code":"0600","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":0.02,"unit":"mg/L","sample_date":"2026-04-02","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 (free)","code":"0700","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":0.27,"unit":"mg/L","sample_date":"2026-04-02","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":0.29,"unit":"mg/L","sample_date":"2026-04-02","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":"Nitrate (as N)","code":"NITRATE","cas_number":"14797-55-8","group":"inorganics","section":"other_detected","measured_value":0.68,"unit":"mg/L","sample_date":"2025-09-03","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":"Haloacetic Acids (HAA5)","code":"2456","cas_number":null,"group":"dbps","section":"other_detected","measured_value":0.91,"unit":"ug/L","sample_date":"2025-09-03","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":2.2,"unit":"ug/L","sample_date":"2025-09-03","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":"Metolachlor","code":"2034","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.008,"unit":"ug/L","sample_date":"2023-07-19","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":"Chromium (total)","code":"CHROMIUM","cas_number":"7440-47-3","group":"inorganics","section":"other_detected","measured_value":1.46,"unit":"ug/L","sample_date":"2022-07-12","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":"Nickel","code":"1036","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.0081,"unit":"mg/L","sample_date":"2023-07-19","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":"Arsenic","code":"ARSENIC","cas_number":"7440-38-2","group":"inorganics","section":"other_detected","measured_value":3,"unit":"ug/L","sample_date":"2018-08-29","source":"WQP","source_scope":"regional_groundwater","health_guideline_value":0.000004,"health_guideline_source":"OEHHA PHG","epa_mcl_value":0.01,"status":"exceeds_guideline","detection_limit":null},{"name":"Atrazine","code":"2050","cas_number":null,"group":"vocs","section":"other_detected","measured_value":0.026,"unit":"ug/L","sample_date":"2024-08-27","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":"Barium","code":"BARIUM","cas_number":"7440-39-3","group":"inorganics","section":"other_detected","measured_value":0.037,"unit":"mg/L","sample_date":"2024-08-27","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":"Gross Alpha Radiation (excluding Radon and 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ECHO","url":"https://echo.epa.gov/"}],"pfas_combined_display":null,"well_counts":{"active":2,"retired":1,"facilities_synced_at":"2026-04-11T13:48:07.246Z"},"historical_wells":[{"state_facility_id":"2","facility_name":"AAM161","deactivation_date":"2024-08-28","top_contaminant":"Gross Alpha","top_contaminant_code":"4000","max_value":31.7,"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":[],"haa5_lraa":[]}