The meter consists of a propeller that is rotated by the action of flowing water. Given the number of revolutions in a given time interval, velocity can be determined for the location of the current meter. Many streamflow data users must make operational decisions daily. For these users, streamflow records are computed and made available on a provisional basis. Computers in the district office convert the depth reading to a value for flow and plot a graph of flow versus time, usually showing the previous 7 days.
Some stations also transmit values for temperature, conductance, or other parameters.
These data then are retransmitted by means of a domestic satellite, and the resulting signal is received by the USGS and other users. The transmission and receipt of the signals are automated, as are the provisional discharge computations that are available for meeting current data needs. More than 4,000 locations are included in the Realtime Streamflow Stations map layer. For more uses see the section - Uses of Streamflow Data . Here are the steps for identifying realtime streamflow stations.