As you will see the gauges below display two different types of measurements. The Middle Fork and the Confluence are measured in ‘Feet‘ and the Main and Whitebird are measured in ‘CFS‘.
Most rivers are measured in ‘cubic feet per second’ (CFS), which is the depth x width x speed, a volume reading. The gauge is a fancy little contraption that spins around in the water to gauge the speed at a set point in the river where the depth and width are pre-measured. The Middle Fork, and a few other rivers, are measured in feet, in which the gauge is a measuring stick in the water at a set location with markings on it like a ruler. The handy aspect of this method is you can float by the gauge and visually see what level the river is at. With CFS, the gauge is digital and the information is sent via transmitter to the internet at which point the public can view the current flow.
Along it’s journey the Middle Fork gains volume from over 100 tributaries which causes a change in the CFS regularly, sometimes 2 or 3 creeks within 100 feet of each other. As a result in it’s 100+ mile journey, the CFS can range from 1,000 to 15,000. So if the gauge was at the beginning of the river it would not accurately reflect the CFS at the end of the river and vice versa. Because of this fact it is more user friendly to measure the river in feet. With this method, the characteristics of the river can be learned according to where the river falls on the feet gauge even though the volume is growing as one travels downstream.