{"id":"us-river-flow","slug":"us-river-flow","name":"United States River Flow Dataset","description":"Annual mean streamflow for long-record United States gauging stations, taken from the USGS statistics service. Every station here has at least fifty years of published record and opened before 1930.","methodology":"Annual mean discharge as published by the USGS statistics service, computed by USGS from its own quality-controlled daily record. Hydrionis does not recompute the mean; it converts cubic feet per second to cubic metres per second — a foot being exactly 0.3048 m, the conversion is exact — and records the publisher’s unit alongside so a value can be checked against the source. Sites are selected per state because the USGS site service does not accept a national query, and a site is kept only where the published statistics themselves span fifty years, which is a stricter test than the period of record advertised in the site listing.","domains":["river-flow"],"metricIds":["river-flow-mean"],"subjectScope":"United States streamgauges opening before 1930 with 50+ years of published statistics","cadence":"annual","version":"1.0.0","released":"2026-08-24","changelog":[{"version":"1.0.0","date":"2026-08-24","summary":"First release, and the first Hydrionis dataset outside the United Kingdom drawn from station-level measurement.","additions":["Annual mean flow for 1,751 long-record United States gauges."]}],"limitations":["Annual means only. Monthly means are published by the same service and are not collected; seasonal behaviour cannot be read from this dataset.","Flow is a property of a gauge on a reach, not of a river, and is affected by upstream regulation, diversion and abstraction. Many long US records sit below major dams built during the record.","The mean is USGS’s own, computed on its water year and methodology. It is not directly comparable with the England series, which Hydrionis computes itself from daily values on calendar years."],"observationCount":148948,"seriesCount":1750,"subjectCount":1750,"from":1874,"to":2025,"sourceIds":["usgs-nwis"],"units":["m³/s"],"redistributable":true,"commerciallyReusable":true,"citation":"Hydrionis (2026), United States River Flow Dataset, version 1.0.0. Retrieved from https://hydrionis.com/data/datasets/us-river-flow/","downloads":[{"file":"/downloads/observations-river-flow-usgs-nwis.csv","format":"CSV","label":"river-flow observations from USGS (646,106 rows)"}],"apiPath":"/api/v1/datasets/us-river-flow.json","lastFetched":"2026-10-01","fields":[{"id":"river-flow-mean","name":"Mean river flow","definition":"Average volumetric discharge past a gauging station over a stated period.","unit":"m³/s","nativeGeography":["river-gauge"],"comparabilityNotes":"Flow is a property of a specific gauge on a specific reach, and cannot be attributed to a river as a whole. Two gauges on the same river can differ by an order of magnitude. Where a station measures flow through a sluice, lock or pumping station — much of the Dutch network does — discharge is signed and a negative value means water moving in the reverse direction, which is a real operating state and not an error. Managed flow of that kind is not comparable with discharge at a natural gauging station, because it reflects operational decisions as well as hydrology."}]}