{"schema_version":"1.2","pwsid":"WI7720165","system_name":"MARSHFIELD UTILITIES","city":"MARSHFIELD","state":"WI","population_served":18815,"source_type":"GW","summary":"MARSHFIELD UTILITIES serves approximately 18,815 people in MARSHFIELD, Wisconsin. Based on contaminant analyses from DNR, EPA ECHO, EPA UCMR5, 1 contaminant has been measured above federal EPA standards (MCL) and 4 exceed health-based guidelines. The most significant finding is Thallium at 0.0025 mg/L, which is 1.3x the EPA legal limit. Data is drawn from source-level compliance monitoring and covers 2016 through 2026. Results reflect conditions at the point of collection (wells, treatment plants), not necessarily at the tap.","data_period":{"start":"2016-09-30","end":"2026-03-24"},"contaminants_tested":131,"contaminants_detected":34,"exceedances":1,"guideline_exceedances":4,"contaminants":[{"name":"Chlorine (free)","code":"0700","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":0.55,"unit":"mg/L","sample_date":"2026-03-24","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":0.64,"unit":"mg/L","sample_date":"2026-03-24","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":15,"retired":12,"facilities_synced_at":"2026-04-11T13:48:07.246Z"},"historical_wells":[],"has_only_historical_data":false,"pfas_hazard_index":{"value":0.193,"compounds_used":["PFHXS","PFNA","PFBS"],"is_partial":true,"threshold":1,"components":[{"code":"PFHXS","value_ng_l":1.6,"hbwc_ng_l":10,"ratio":0.16},{"code":"PFNA","value_ng_l":0.324,"hbwc_ng_l":10,"ratio":0.0324},{"code":"PFBS","value_ng_l":1.2,"hbwc_ng_l":2000,"ratio":0.0006}]},"tthm_lraa":[{"monitoring_point":"system_wide","value":26.85,"unit":"ug/L","quarters_used":["2024Q3","2025Q1","2025Q3","2026Q1"],"sample_count":8,"mcl":80,"exceeds_mcl":false}],"haa5_lraa":[{"monitoring_point":"system_wide","value":10.34,"unit":"ug/L","quarters_used":["2024Q3","2025Q1","2025Q3","2026Q1"],"sample_count":8,"mcl":60,"exceeds_mcl":false}]}