{"schema_version":"1.2","pwsid":"WI1130250","system_name":"OAKHILL CORRECTIONAL INST","city":"OREGON","state":"WI","population_served":1096,"source_type":"GW","summary":"OAKHILL CORRECTIONAL INST serves approximately 1,096 people in OREGON, Wisconsin. Based on contaminant analyses from DNR, WQP, EPA ECHO, 0 contaminants have been measured above federal EPA standards (MCL) and 3 exceed health-based guidelines. The most significant finding is Arsenic at 0.0011 mg/L, which is 275x 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":"2026-03-09"},"contaminants_tested":83,"contaminants_detected":18,"exceedances":0,"guideline_exceedances":3,"contaminants":[{"name":"Thallium","code":"1038","cas_number":null,"group":"inorganics","section":"guideline_exceedance","measured_value":0.000714,"unit":"mg/L","sample_date":"2026-03-09","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.0005,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.002,"status":"exceeds_guideline","detection_limit":null},{"name":"Antimony","code":"1052","cas_number":null,"group":"inorganics","section":"other_detected","measured_value":0.00123,"unit":"mg/L","sample_date":"2026-03-09","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.006,"health_guideline_source":"EPA 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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":2.1,"unit":"mg/L","sample_date":"2026-03-09","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":"Total Trihalomethanes (TTHMs)","code":"2950","cas_number":null,"group":"dbps","section":"other_detected","measured_value":3.13,"unit":"ug/L","sample_date":"2025-08-04","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":2.45,"unit":"ug/L","sample_date":"2025-08-04","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 Xylenes","code":"2969","cas_number":"1330-20-7","group":"organic","section":"other_detected","measured_value":1.2,"unit":"ug/L","sample_date":"2024-07-10","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":0.21,"unit":"ug/L","sample_date":"2023-05-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":null},{"name":"Arsenic","code":"ARSENIC","cas_number":"7440-38-2","group":"inorganics","section":"guideline_exceedance","measured_value":0.0011,"unit":"mg/L","sample_date":"2023-05-15","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.000004,"health_guideline_source":"OEHHA 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ECHO","source_scope":"federal_program","health_guideline_value":0.0002,"health_guideline_source":"OEHHA 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":390,"unit":"ug/L","sample_date":"2023-07-19","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":"PFBS (Perfluorobutane Sulfonate)","code":"PFBS","cas_number":"375-73-5","group":"pfas","section":"pfas","measured_value":0.47,"unit":"ng/L","sample_date":"2023-05-15","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 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ECHO","url":"https://echo.epa.gov/"}],"pfas_combined_display":null,"well_counts":{"active":2,"retired":0,"facilities_synced_at":"2026-04-11T13:48:07.246Z"},"historical_wells":[],"has_only_historical_data":false,"pfas_hazard_index":{"value":0.1102,"compounds_used":["PFHXS","PFBS"],"is_partial":true,"threshold":1,"components":[{"code":"PFHXS","value_ng_l":1.1,"hbwc_ng_l":10,"ratio":0.11},{"code":"PFBS","value_ng_l":0.47,"hbwc_ng_l":2000,"ratio":0.0002}]},"tthm_lraa":[{"monitoring_point":"system_wide","value":3.13,"unit":"ug/L","quarters_used":["2022Q3","2023Q3","2024Q3","2025Q3"],"sample_count":4,"mcl":80,"exceeds_mcl":false}],"haa5_lraa":[]}