Yellowstone National Park — River Levels & Flows

The Firehole, Madison, Lamar and Yellowstone — inside the park boundary. Big Buoy shows live USGS river gauges across WY, MT, with stage, flow and a 7-day trend for each, plus National Weather Service flood categories where they are published.

About Yellowstone National Park

Ten gauges sit inside the park, and between them they cover nearly every river people come here to fish: the Yellowstone at the lake outlet, the Madison, the Lamar, the Gibbon, the Gardner and both Firehole stations, one of them at Old Faithful. Two things make these numbers read differently from a lowland river. The park sits high — most of it above 7,000 feet — so flows are snowmelt-driven and runoff can hold into summer, and the Firehole runs through thermal basins that warm it, which is why its summer temperature matters as much as its level. The Lamar and Soda Butte are freestone: they clear fast and colour up faster after a storm. Absolute discharge here is small next to a big river, so read these gauges against themselves rather than against water elsewhere. Park fishing has its own season, permits and closures — check the National Park Service before you go.

How to read these gauges

Flow (discharge, in cubic feet per second) is comparable between gauges and is usually the better number for judging whether a river is up or down. Stage is the water height in feet above each gauge's own local datum, so it is local: the same 4 ft describes different rivers at two different gauges. Readings older than three times a gauge's reporting interval are shown as last reported rather than as current conditions, and a gauge that reports nothing is shown as not reported — never as zero.

Data: USGS National Water Information System. Flood categories: NOAA/National Weather Service.