Stations Most automated river gages in Washington and Idaho are maintained by the U.S. Geological Survey. However, a small percentage of gages are owned by the U.S. Army Corps of Engineers, the Bureau of Reclamation and the National Weather Service. These gages record the river stage every 15 minutes. Communication with these automated gages is done in one of two ways. River data from these sites is downloaded by a modem, generally about once an hour.
Some river gaging sites depend entirely on humans to visually inspect the data.
One way is through the use of a wire weight gage , small grey boxes which are generally installed on the sides of bridges. These gages have a weight which can be lowered from a measured height down to the surface of the water. The distance from the gage to the top of the river is then used to calculate the river stage. The simplest way to gage a river is by using a staff gage . This is essentially a board with increments of feet inscribed on it.