{"schema_version":"1.2","pwsid":"IL1970250","system_name":"CREST HILL","city":"CREST HILL","state":"IL","population_served":21169,"source_type":"GW","summary":"CREST HILL serves approximately 21,169 people in CREST HILL, Illinois. Based on contaminant analyses from EPA ECHO, EPA UCMR5, 2 contaminants have been measured above federal EPA standards (MCL) and 4 exceed health-based guidelines. The most significant finding is PFOA (Perfluorooctanoic Acid) at 0.0137 ug/L, which is 3.4x the EPA legal limit. Data is drawn from source-level compliance monitoring and covers 2018 through 2025. Results reflect conditions at the point of collection (wells, treatment plants), not necessarily at the tap.","data_period":{"start":"2018-12-31","end":"2025-12-31"},"contaminants_tested":32,"contaminants_detected":10,"exceedances":2,"guideline_exceedances":4,"contaminants":[{"name":"Lead (90th Percentile)","code":"PB90","cas_number":"7439-92-1","group":"lead_copper","section":"guideline_exceedance","measured_value":0.00214,"unit":"mg/L","sample_date":"2025-12-31","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":"CU90","cas_number":"7440-50-8","group":"lead_copper","section":"guideline_exceedance","measured_value":1.686,"unit":"mg/L","sample_date":"2023-06-30","source":"EPA ECHO","source_scope":"federal_program","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":0.0259,"unit":"ug/L","sample_date":"2023-12-28","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":"PFBA (Perfluorobutanoic Acid)","code":"PFBA","cas_number":null,"group":"pfas","section":"pfas","measured_value":0.0188,"unit":"ug/L","sample_date":"2023-12-28","source":"EPA UCMR5","source_scope":"federal_program","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":0.005},{"name":"PFBS (Perfluorobutane Sulfonate)","code":"PFBS","cas_number":"375-73-5","group":"pfas","section":"pfas","measured_value":0.0437,"unit":"ug/L","sample_date":"2023-12-28","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":"Lithium","code":"lithium","cas_number":null,"group":"other","section":"pfas","measured_value":34.8,"unit":"ug/L","sample_date":"2023-12-28","source":"EPA UCMR5","source_scope":"federal_program","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":9},{"name":"PFHxS (Perfluorohexane Sulfonate)","code":"PFHXS","cas_number":"355-46-4","group":"pfas","section":"legal_violation","measured_value":0.0122,"unit":"ug/L","sample_date":"2023-12-28","source":"EPA UCMR5","source_scope":"federal_program","health_guideline_value":0.01,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.01,"status":"exceeds_legal_limit","detection_limit":0.003},{"name":"PFOA (Perfluorooctanoic Acid)","code":"PFOA","cas_number":"335-67-1","group":"pfas","section":"legal_violation","measured_value":0.0137,"unit":"ug/L","sample_date":"2023-12-28","source":"EPA UCMR5","source_scope":"federal_program","health_guideline_value":0,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.004,"status":"exceeds_legal_limit","detection_limit":0.004},{"name":"Pfhxa","code":"PFHxA","cas_number":null,"group":"other","section":"pfas","measured_value":0.0223,"unit":"ug/L","sample_date":"2023-12-28","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":"Pfhpa","code":"PFHpA","cas_number":null,"group":"other","section":"pfas","measured_value":0.0133,"unit":"ug/L","sample_date":"2023-12-28","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}],"sources":[{"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":null,"well_counts":{"active":8,"retired":2,"facilities_synced_at":"2026-09-06T14:49:36.593Z"},"historical_wells":[],"has_only_historical_data":false,"pfas_hazard_index":{"value":1.2419,"compounds_used":["PFHXS","PFBS"],"is_partial":true,"threshold":1,"components":[{"code":"PFHXS","value_ng_l":12.2,"hbwc_ng_l":10,"ratio":1.22},{"code":"PFBS","value_ng_l":43.7,"hbwc_ng_l":2000,"ratio":0.0219}]},"tthm_lraa":[],"haa5_lraa":[]}