Gage height is the height of the water surface above a reference point at a particular gauge. Streamflow, or discharge, is the volume of water moving past that point during a period of time. In the United States, streamflow is commonly shown in cubic feet per second.
The two values are related at many river gauges, but they are not interchangeable. USGS hydrologists develop a stage–discharge rating from field measurements. Channel shape, vegetation, sediment, ice, backwater, and control structures can change that relationship. The same gage height may therefore correspond to a different discharge after conditions change.
What each measurement can tell you
Gage height is often useful for comparing the river surface with locally defined reference levels. Streamflow is useful for understanding the amount of water moving through the channel. Neither number alone establishes whether a river is navigable, swimmable, or flood-free.
LakeRiverNow always labels the parameter and unit, keeps the station relationship visible, and links the official source. If a flood category is displayed later, it must come from an appropriate official threshold—not from a generic interpretation of gage height.