Water-surface elevation of US rivers over the last 7 days at 15-minute steps, in metres above the EGM2008 geoid.
USGS stream gauges: the mean of each gauge's readings within each 15-minute step, plus the gauge's datum converted to EGM2008. Gauges without a known EGM2008 datum show gage height instead.
SWOT river nodes (about 200 m apart) whose level is reconstructed every 15 minutes from the two nearest USGS gauges up- and downstream. Each node's link to its gauges was fitted to SWOT satellite passes from 2023 to 2026 with BRACE, a Bayesian model. The line is the median and the band the 5–95% range. Dots mark SWOT passes within the week. They are estimates, not measurements.
Low-skill virtual gauges are nodes whose fit matched the SWOT passes poorly (NSE below 0.5 or RMSE above 1 m). They are hidden unless you switch them on under Sites.
Each site is compared with its own 15-minute record since March 2023, up to the start of the current month. The class is set by the highest value in the last 24 hours: above normal means above the level the site exceeds 1% of the time, high 0.1% of the time, and record above the highest level in its record. Sites with less than a year of record have no class. These are statistical levels, not NWS flood stages.
The data are refreshed every day at 06:00 US Mountain time and cover the last 7 complete UTC days.
Sources: USGS Water Data (instantaneous values), NASA/CNES SWOT L2 RiverSP, SWORD. Basemap © OpenFreeMap, © OpenStreetMap contributors.