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What is a Gaging Station?

Stream Discharge Monitoring

Gaging stations are facilities used by hydrologists to automatically monitor streams, wells, lakes, canals, reservoirs and or other water bodies. Instruments at these stations collect information such as water height, discharge, water chemistry and water temperature.

The US Geological Survey has gaging stations at thousands of locations across the United States. Each dot on the map below represents one USGS stream gaging station in their real-time stream flow data system.

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These stations collect information about the stream and transmit it to the USGS via a satellite communication system. The data is then processed and delivered to the public via the internet.

Measurements from these stations are useful for a wide variety flood prediction, water management, recreation and navigation purposes. USGS realizes the public demand for this information and allows anyone to use it. Check on a stream Gaging Station near your home.

Illustrations are from the US Geological Survey.

There are many different types of stream gages. The photos blow will give you some idea of their variety, expense, size and technical basis. All of these gages measure the stage of the stream (height of the water above a datum). Stage values can be converted into discharge values if a rating curve has been estabilshed for the stream at that location.

Staff Gage

The simplest stream gage. A "giant ruler" mounted on a pier, bridge support, post or colum. Stage height is read manually.



Wire Weight Gage

Permanently mounted on the side of a bridge a wire weight gage has a weight, a reel of wire, and a manual crank. The weight is lowered until it touches the water. A calibrated spool accurately determines how much wire was required for the weight to reach the water. This number is used to calculate the stage of the stream.


Vertical Pipe Gage

This type of gage is mounted above a pipe that penetrates the bottom of the stream or sediments along the stream's bank. Water flows into the pipe through perforations or through the sediment and fills it to the same level as the water in the stream. Pressure sensors or a float/wire system is used to determine the height of the water. Some of these gages record the height of the water in a memory - which is then downloaded to a laptop during occasional visits by the hydrologist.





Gage House

A permanent house that holds stream gaging equipment - typically a gage of some type, a computer, and a satellite uplink. Frequently a stilling well or a vertical pipe is beneath the gage house.

Illustrations are from USGS and NOAA.

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