{"schema_version":"1.2","pwsid":"WI4590454","system_name":"GRESHAM WATERWORKS","city":"GRESHAM","state":"WI","population_served":534,"source_type":"GW","summary":"GRESHAM WATERWORKS serves approximately 534 people in GRESHAM, Wisconsin. Based on contaminant analyses from DNR, WQP, EPA ECHO, 1 contaminant has been measured above federal EPA standards (MCL) and 4 exceed health-based guidelines. The most significant finding is Gross Alpha Radiation (excluding Radon and Uranium) at 51.3 pCi/L, which is 3.4x the EPA legal limit. Data is drawn from source-level compliance monitoring and covers 2002 through 2026. Results reflect conditions at the point of collection (wells, treatment plants), not necessarily at the tap.","data_period":{"start":"2002-08-20","end":"2026-03-25"},"contaminants_tested":13,"contaminants_detected":13,"exceedances":1,"guideline_exceedances":4,"contaminants":[{"name":"Chlorine (free)","code":"0700","cas_number":null,"group":"disinfectants","section":"other_detected","measured_value":0.43,"unit":"mg/L","sample_date":"2026-03-25","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":"Combined Radium (226+228)","code":"4010","cas_number":null,"group":"radionuclides","section":"other_detected","measured_value":2.384,"unit":"pCi/L","sample_date":"2026-03-04","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0,"health_guideline_source":"EPA MCLG","epa_mcl_value":5,"status":"below_limits","detection_limit":null},{"name":"Uranium","code":"4006","cas_number":"7440-61-1","group":"radionuclides","section":"guideline_exceedance","measured_value":3.33,"unit":"ug/L","sample_date":"2026-03-04","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.0005,"health_guideline_source":"OEHHA PHG","epa_mcl_value":0.03,"status":"exceeds_guideline","detection_limit":null},{"name":"Gross Alpha Radiation (excluding Radon and Uranium)","code":"4000_EXCL","cas_number":null,"group":"radionuclides","section":"legal_violation","measured_value":51.3,"unit":"pCi/L","sample_date":"2026-03-04","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":15,"status":"exceeds_legal_limit","detection_limit":null},{"name":"Haloacetic Acids (HAA5)","code":"2456","cas_number":null,"group":"dbps","section":"other_detected","measured_value":8.04,"unit":"ug/L","sample_date":"2025-07-16","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":25.66,"unit":"ug/L","sample_date":"2025-07-16","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":"Nitrate (as N)","code":"NITRATE","cas_number":"14797-55-8","group":"inorganics","section":"other_detected","measured_value":0.95,"unit":"mg/L","sample_date":"2025-02-19","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":"Barium","code":"BARIUM","cas_number":"7440-39-3","group":"inorganics","section":"other_detected","measured_value":0.028,"unit":"mg/L","sample_date":"2023-09-20","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":"Fluoride (natural)","code":"FLUORIDE","cas_number":"16984-48-8","group":"inorganics","section":"other_detected","measured_value":0.87,"unit":"mg/L","sample_date":"2023-09-20","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":"Gross Beta","code":"4002","cas_number":null,"group":"radionuclides","section":"other_detected","measured_value":3.63,"unit":"pCi/L","sample_date":"2023-06-14","source":"DNR","source_scope":"source_monitoring","health_guideline_value":null,"health_guideline_source":null,"epa_mcl_value":50,"status":"below_limits","detection_limit":null},{"name":"Radon","code":"RADON","cas_number":"10043-92-2","group":"radionuclide","section":"guideline_exceedance","measured_value":3060,"unit":"pCi/L","sample_date":"2023-02-22","source":"DNR","source_scope":"source_monitoring","health_guideline_value":300,"health_guideline_source":"EPA proposed MCL (1999, never finalized)","epa_mcl_value":null,"status":"exceeds_guideline","detection_limit":null},{"name":"Arsenic","code":"ARSENIC","cas_number":"7440-38-2","group":"inorganics","section":"other_detected","measured_value":0.56,"unit":"ug/L","sample_date":"2023-08-22","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":"Chromium (total)","code":"CHROMIUM","cas_number":"7440-47-3","group":"inorganics","section":"other_detected","measured_value":1.2,"unit":"ug/L","sample_date":"2023-08-22","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":"Lead (90th Percentile)","code":"PB90","cas_number":"7439-92-1","group":"lead_copper","section":"guideline_exceedance","measured_value":0.00093,"unit":"mg/L","sample_date":"2023-09-30","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":"COPPER","cas_number":"7440-50-8","group":"lead_copper","section":"other_detected","measured_value":200,"unit":"ug/L","sample_date":"2023-09-27","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.3,"health_guideline_source":"OEHHA PHG","epa_mcl_value":null,"status":"below_limits","detection_limit":null}],"sources":[{"name":"DNR","url":"https://apps.dnr.wi.gov/dwsportalpub"},{"name":"WQP","url":"https://www.waterqualitydata.us/"},{"name":"EPA 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":[],"has_only_historical_data":false,"pfas_hazard_index":null,"tthm_lraa":[{"monitoring_point":"system_wide","value":25.66,"unit":"ug/L","quarters_used":["2022Q3","2023Q3","2024Q3","2025Q3"],"sample_count":4,"mcl":80,"exceeds_mcl":false}],"haa5_lraa":[{"monitoring_point":"system_wide","value":8.04,"unit":"ug/L","quarters_used":["2022Q3","2023Q3","2024Q3","2025Q3"],"sample_count":4,"mcl":60,"exceeds_mcl":false}]}