USGS Streamflow API
Live river and stream conditions from the USGS Water Services network. The catalogue of 16,900+ active US streamflow gauges is searchable by name, state or coordinate; the live endpoint returns the latest observation for any gauge: streamflow / discharge (in cubic feet per second and m³/s) and gauge height (in feet and metres), with the station name, observation time and coordinates. Find the gauges nearest any lat/lon. Ideal for flood monitoring, hydrology, whitewater/fishing & recreation apps, drought tracking and environmental dashboards.
api.oanor.com/streamflow-api