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Water Science Pictures
Wire recorder for recording stream heights

The U.S. Geological Survey has thousands of stream-gaging systems installed nationwide. These systems measure the heights of the water in streams. After some computations, the amount of water flowing can be computed. The technology is changing. The more modern systems detect the heights of streams and transmit that information via satellites to a USGS office. But in the past, wire recorders like this one maintained our gage-height recording network.

Here's how these recorders work: This recorder is kept in a box (made of metal to resist bullets!) on top of a large metal pipe going down into the water. The round wheel in front has a metal wire wrapped around it holding a float at one end. As the water in the stream moves up and down, the water in the stilling well moves, too. The float on the wire goes up and down with the water. As the wire moves, it moves the ink pen, which records the stream height on rolling paper, operated by a battery. When technicians visit the site, they remove the paper roll and take it back at to the office where they will analyze it.

With all these moving parts, you can see the opportunity for trouble. The newer automated instruments are more reliable and more efficient.