{"nature":"This API supplies data organisation and trend description only. It is not a recommendation to act; the decision is yours. Purely descriptive - no judgement, no prediction. Every record carries an official source plus a record_hash (canonical sha256, recomputable offline for self-verification; cross-check with free /gauge/verify).","tier":"raw(free base)","record_hash_verifiable":{"mode":"via-endpoint","note":"This response is a projected delivery (some core fields are omitted to control size). Cross-check record_hash with the free /gauge/verify, or buy /gauge to get the complete core for offline recomputation."},"note":"The hydrology CURRENT reading is free (equivalent to the public USGS output). Cross-period comparison (previous/change/trend_7d, on the same basis: real-time against real-time), the official and statistical rulers (band/percentile), and source tiering plus independence labelling (source_tier / sources[].independent) are our added value, not public data. Add-ons: /gauge/ruler, /gauge/calibrated, /gauge/strata, /gauge/history, or pay once for the full /gauge. Current price of each endpoint is at /manifest.","deprecation":{"effective_date":"2026-08-08","fields_removed":["previous","change","trend_7d","sources","source_agreement_cv","source_tier"],"reason":"Only current is equivalent to the public USGS output. Cross-period comparison (on the same basis: real-time against real-time), source tiering and independence labelling are our own processing.","use_instead":{"all":"/gauge (full single-signal delivery)","price_source":"/manifest"},"unchanged":"The hydrology current reading (current) and record_hash stay free. This endpoint is limited to the single hydrology.* line and is kept as a try-before-you-buy shop window."},"signal_id":"hydrology.river-level","entity":"07010000","entity_name":"Mississippi River at St. Louis, MO","snapshot_date":"2026-08-19","observed_at":"2026-08-19T04:30:00.000Z","data_age_hours":1,"current":{"gauge_height_ft":13.1},"previous":{"gauge_height_ft":13.35},"change":{"period":"vs_24h_ago (instantaneous vs instantaneous, same basis)","gauge_height_ft":{"delta":-0.25,"direction":"falling","direction_reason":null}},"trend_7d":[5.76,5.81,5.68,6.28,9.65,12.72,13.33],"sources":[{"name":"USGS Water Services","role":"sole data source (IV real-time current value; dv daily mean supplies trend_7d)","as_of":"2026-08-19T04:30:00.000Z","value":13.1,"weight":1,"independent":true},{"name":"NOAA NWS/NWPS","role":"Flood threshold and official classification provider; its observation is the official relay channel of the same USGS sensor (NWPS self-reports usgsId=07010000), not an independent second source","as_of":"2026-08-19T04:30:00Z","value":13.1,"weight":0,"relay_of":"USGS 07010000","independent":false}],"source_agreement_cv":null,"source_ref":"https://waterdata.usgs.gov/monitoring-location/07010000/","source_tier":"T1","record_hash":"sha256:f5c1e56ac685ffd91093d8cb671b918282038c492cac66b9a7c335e9c241ff17"}