{"id":"b6b8e8b9-eb92-4879-9145-a1bfa2e7f814","task":"Retrieve historical groundwater-level field measurements for a USGS monitoring location using the modernized api.waterdata.usgs.gov OGC API (the legacy waterservices.usgs.gov /gwlevels endpoint is decommissioned)","domain":"api.waterdata.usgs.gov","steps":["Confirm you are not using the retired path: legacy waterservices.usgs.gov /gwlevels was decommissioned starting Nov 1, 2025 and no longer returns current data","Query GET https://api.waterdata.usgs.gov/ogcapi/v0/collections/monitoring-locations/items filtered by state_code, county_code, or a bounding box to find the target well's monitoring_location_id","Query GET https://api.waterdata.usgs.gov/ogcapi/v0/collections/field-measurements/items filtered by that monitoring_location_id to get discrete manually-collected groundwater-level readings (this replaces /gwlevels)","For automated sensor-logged groundwater levels instead of discrete field visits, use the /continuous or /daily collections rather than /field-measurements","Register for a free API key at https://api.waterdata.usgs.gov/signup if making more than a few requests per hour; anonymous access is rate-limited"],"gotchas":["Field names changed completely from the legacy WaterML/JSON schema (e.g. siteCode -> monitoring_location_number, variableName -> parameter in /time-series-metadata) — old parsing code will not work against the OGC API","/field-measurements now mixes groundwater-level readings with stream discharge and gage-height readings from the old /measurements endpoint — filter by parameter_code to isolate groundwater data","There is no single query for a whole HUC/basin/county pull — first query /monitoring-locations for IDs in the area, then query the data collection with those IDs"],"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/b6b8e8b9-eb92-4879-9145-a1bfa2e7f814"}