Measuring Streamflow for More Than a Century

By Steve Vandas

First streamflow station, on the Rio Grande near Embudo, New Mexico. Cable way for measuring streamflow at high flow is at the right, and the gage shelter is the building at the left.

USGS stream gages provide the hydrologic information needed to define, use, and manage the Nation's water resources. This information was critical for the settling of the West, and water continues to be one of the Nation's major issues into the 21^st century. The development of data on the flow of the Nation's rivers mirrored the development of the country. In the 1880's, personnel from the Irrigation Survey, which was then a branch of the USGS, were directed by Director John Wesley Powell to develop procedures that could be used to produce reliable streamflow estimates. Powell felt that it was important to inventory the flow of streams in the arid west prior to settlement.

Increasing need for reliable water supplies quickly led to the need for streamflow data with which to design storage and distribution facilities. In 1889, the first stream-gaging station operated in the United States by the USGS was established on the Rio Grande near Embudo, NM. The establishment of this early station was an outgrowth of efforts to train individuals to measure the flow of rivers and streams and to define standard stream-gaging procedures. As soon as methods were developed at Embudo, personnel were dispersed to collect streamflow data at other western locations.

Within 2 years, the first streamflow measurement in the East was made on the Potomac River at Chain Bridge, near Washington, DC, and a gaging station was established there on May 1, 1891. By 1895, discharge measurements were being made by USGS in at least 27 states. Today, the USGS operates and maintains approximately 7,000 streamgages, which provide long-term, accurate, and unbiased information that meets the needs of many diverse users in the United States, Puerto Rico, and the Trust Territories of the Pacific Islands. More than 90 percent of these stations are operated with at least partial support from other Federal, State, and local agencies. Much of the streamflow information collected from these gages can be accessed in real time, providing water managers and other users with up-to-the-minute information about streamflow around the country. Real-time streamflow for selected locations in the United States can be obtained at http://waterdata.usgs.gov/nwis/rt.