Migrate discrete groundwater-level queries from USGS legacy /gwlevels to the new /field-measurements API
domain: api.waterdata.usgs.gov · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Legacy discrete groundwater-level readings from https://waterservices.usgs.gov/nwis/gwlevels are now served from https://api.waterdata.usgs.gov/ogcapi/v0/collections/field-measurements (OGC API - Features).
Query field-measurements filtered to a site, e.g. GET /ogcapi/v0/collections/field-measurements/items?monitoring_location_id=USGS-403836085374401.
Field names changed: siteCode/agencyCode collapse into monitoring_location_id; dateTime becomes an ISO 8601 time field; the old "P"/"A" qualifier codes are now the approval_status field.
This endpoint does not carry continuous sensor groundwater levels - use /continuous for automated readings and /daily for daily summary values instead.
Sign up for a free api.data.gov-issued key if you'll exceed the anonymous rate limit, and pass it via api_key= or the X-Api-Key header.
Known gotchas
The response is one JSON feature per observation, not the old timeSeries-grouped shape - parsers built for legacy WaterServices JSON need rewriting, not just a URL swap.
USGS's own migration guide lists several old fields (e.g. qualifierDescription, method info) as "not currently available" in the new API - don't assume full field parity.
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