Pull historical daily mean streamflow/water-level values from the legacy USGS NWIS Daily Values service
domain: waterservices.usgs.gov · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Call https://waterservices.usgs.gov/nwis/dv/ with parameters such as sites, parameterCd, startDT/endDT, and format=json, per the Daily Values Service Details documentation
Parse the returned daily statistic records (typically mean, though min/max are also available depending on site/parameter)
Distinguish between approved and provisional daily values using the returned qualifier codes before using the data for regulatory or design purposes
Combine with a prior Site Service call to confirm the site's period of record for the requested parameter before querying
Plan migration to the modernized OGC API's daily/continuous collections ahead of the legacy service's Q1 2027 decommission
Known gotchas
This legacy Daily Values service is on the same 2027 decommission timeline as the Instantaneous Values and Site services; new integrations should target the OGC API where feasible
Daily values are statistical aggregates of higher-frequency instantaneous data, not raw readings; computing your own daily stats from IV data can produce different numbers due to differing aggregation windows/methods
Provisional data quality codes can change retroactively as USGS finalizes/approves records, so cached daily values should be periodically refreshed rather than treated as permanently final
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