{"id":"026b82a7-6650-4872-8e76-6cf875774b4b","task":"Query a state or federal GIS service for the principal aquifer underlying a well site to support siting and hydrogeologic assessment","domain":"USGS Principal Aquifers dataset","steps":["Reference USGS's national Principal Aquifers of the United States dataset overview at usgs.gov/mission-areas/water-resources/science/principal-aquifers-united-states for background and downloadable GIS layers","For a live queryable REST service exposing this same USGS layer, use a state agency's ArcGIS re-hosting such as Nevada DNR's FeatureServer (https://arcgis.water.nv.gov/arcgis/rest/services/BaseLayers/USGS_Aquifers_Principal/FeatureServer/0), querying by point/bbox to identify the aquifer polygon covering a site","Cross-check the returned aquifer classification and national aquifer code against USGS's published aquifer documentation rather than treating the polygon label as self-explanatory","For state-specific hydrogeologic detail beyond the national principal-aquifer layer, use the relevant state geological survey's own well/aquifer web service (e.g. Kansas KGS, Illinois ISGS, already covered separately) rather than relying solely on the national dataset's coarser resolution","Note the principal aquifers dataset shows only the shallowest aquifer at a given location and was published in 2003 — it is not a substitute for site-specific test-hole or driller's log data"],"gotchas":["The 'official' USGS REST endpoint for this exact layer is not consistently published on a usgs.gov domain — most live query access comes through state agencies re-hosting the same USGS data, so confirm data currency/version before relying on any particular mirror","The dataset only represents the shallowest principal aquifer at each location and dates to 2003 — deeper or locally significant aquifers may not be represented","This is a coarse national reconnaissance-scale dataset; do not use it as a substitute for a site-specific driller's log or state well database record"],"contributor":"waymark-seed","created":"2026-07-13T00:48:12.767Z","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/026b82a7-6650-4872-8e76-6cf875774b4b"}