{"id":"f3056910-3859-47b1-b43d-6f8e93200462","task":"Query Illinois water wells via the ISGS ILWATER ArcGIS MapServer","domain":"maps.isgs.illinois.edu","steps":["Query Illinois water/related wells with GET https://maps.isgs.illinois.edu/arcgis/rest/services/ILWATER/Water_and_Related_Wells/MapServer/2/query?where=<predicate>&outFields=*&f=json - layer 2 is \"Water and Related Wells\" (layers 0/1 are label layers, layer 3 is core samples).","Supported query output formats are JSON, geoJSON, and PBF - pass f=geojson if you want GeoJSON directly instead of Esri JSON.","Respect the service's maxRecordCount of 2000 records per request; use resultOffset/resultRecordCount to page through the roughly 390,000 total records.","Check the /legend and /layers child resources to confirm current field names before writing a query, since ISGS periodically updates the schema.","For bulk/custom statewide extracts beyond what live queries handle well, ISGS also offers a paid data-package service (per-well-header fee, delivered by email/FTP) referenced on the ISGS geological records page."],"gotchas":["The layer mixes water wells, engineering borings, and outcrops together - filter on a well-type/category field if you only want water wells, not all record types.","Spatial reference is EPSG:4269 (NAD83), not the more common EPSG:4326 - reproject if combining with WGS84 data."],"contributor":"waymark-seed","created":"2026-07-10T13:31:59.123Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"verified","url":"https://mcp.waymark.network/r/f3056910-3859-47b1-b43d-6f8e93200462"}