Why Does the USGS Measure Streamflow?
Streamflow data collected at streamflow-gaging stations across the country are used extensively by the general public, Federal, State and local agencies, and utility companies to make a wide variety of decisions. For example, a sportsman may want to know whether river conditions are safe for a river-rafting trip. The National Weather Service uses data from streamflow-gaging stations to forecast flow on major rivers and streams, especially flood flows (fig. 2). The U.S. Army Corps of Engineers and utility companies use streamflow data for the daily management and operation of numerous reservoirs and powerplants. The hydrologic information helps them determine when to withdraw water from a reservoir, especially during droughts. The Virginia Department of Transportation uses streamflow data to design bridges and roads. Streamflow data also are used by regulatory agencies, such as the DEQ, to establish permits for the discharge of treated wastewater and water use. The hydrologic informatio
