{"schema_version":"1.2","pwsid":"IL0990800","system_name":"OTTAWA","city":"OTTAWA","state":"IL","population_served":18097,"source_type":"GW","summary":"OTTAWA serves approximately 18,097 people in OTTAWA, Illinois. Based on contaminant analyses from 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. 1 contaminant exceeds health-based guidelines. The most significant finding is Lead (90th Percentile) at 0.00497 mg/L, which is 24.8x the health guideline. Data is drawn from source-level compliance monitoring and covers 2016 through 2025. Results reflect conditions at the point of collection (wells, treatment plants), not necessarily at the tap.","data_period":{"start":"2016-12-31","end":"2025-12-31"},"contaminants_tested":31,"contaminants_detected":2,"exceedances":0,"guideline_exceedances":1,"contaminants":[{"name":"Lead (90th Percentile)","code":"PB90","cas_number":"7439-92-1","group":"lead_copper","section":"guideline_exceedance","measured_value":0.00497,"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":"Lithium","code":"lithium","cas_number":null,"group":"other","section":"pfas","measured_value":13.1,"unit":"ug/L","sample_date":"2025-09-10","source":"EPA UCMR5","source_scope":"federal_program","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":null,"status":"detected","detection_limit":9}],"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":5,"retired":1,"facilities_synced_at":"2026-09-06T14:49:36.593Z"},"historical_wells":[],"has_only_historical_data":false,"pfas_hazard_index":null,"tthm_lraa":[],"haa5_lraa":[]}