Nevada Water Science Center
During storms, USGS field crews travel to many sites along rivers and streams to measure streamflow. What do we mean exactly when we say we measure streamflow?
Discharge is the amount of water passing a particular point in a stream for a certain period of time. We usually use cubic feet per second (cfs) to describe the discharge in a stream.
For many streams, USGS uses a streamgage to determine streamflow. A streamgage uses a pressure transducer or floats inside a stilling well to measure river stage. A data logger, inside the gagehouse, stores the river stage data until the data is transmitted back to the USGS office. Data is transmitted back to the USGS office every hour. At the USGS office, a rating curve relating stage to streamflow is applied to determine discharge. The streamflow measurements described above are used to define the rating curve. The stage and discharge measurements are both then sent to NWISweb.
All USGS data is stored in the USGS National Water Information System (NWIS). Our stage and streamflow data are available through NWISweb, a web interface to NWIS. You can also access NWIS data through the NWIS mapper which provides a map interface to find data.
USGS has produced a short video about what a streamgage is and what it does for you.
U.S. Geological Survey Fact Sheet 2013-3004
Streamflow data are available on the Nevada WSC web page (http://nevada.usgs.gov/water/index.htm) in real time. Longterm data (greater than 5 years of continuous record) provide baseline data that can be used to analyze peak, mean, and low flows. Data can also be used to determine flood frequency...
U.S. Geological Survey Fact Sheet 2011-3001
Information on the flow of rivers and streams is a vital national asset that safeguards lives, protects property, and ensures adequate water supplies for the future...
U.S. Geological Survey Fact Sheet 2005-3131
The U.S. Geological Survey (USGS) started its first streamgage in 1889 on the Rio Grande River in New Mexico to help determine if there was adequate water for irrigation purposes to encourage new development and western expansion...