The other thing to remember about gauges is that it only measures flow at one point. That will be accurate if you are paddling right below the gauge. Otherwise, as harris mentioned, side streams and general runoff will increase the flow the farther downstream of the gauge you get.
This is a classic problem at Snake Rapid (Hass hole). The gauge is at Palmers Rapids, and a lot of water can be added between there and Snake. Today, the gauge is reading 115, but I imagine at least another 10 cms is coming in from Snake creek, just above the rapid, possibly another 20 cms from other sources.