Skip to main content
U.S. flag

An official website of the United States government

Streamflow of 2015—Water year national summary

August 30, 2016


The maps and graphs in this summary describe national streamflow conditions for water year 2015 (October 1, 2014, to September 30, 2015) in the context of the 86-year period 1930–2015, unless otherwise noted. The illustrations are based on observed data from the U.S. Geological Survey’s (USGS) National Streamflow Information Program The period 1930–2015 was used because prior to 1930, the number of streamgages was too small to provide representative data for computing statistics for most regions of the country.

In the summary, reference is made to the term “runoff,” which is the depth to which a river basin, State, or other geographic area would be covered with water if all the streamflow within the area during a specified time period was uniformly distributed upon it. Runoff quantifies the magnitude of water flowing through the Nation's rivers and streams in measurement units that can be compared from one area to another.

Each of the maps and graphs can be expanded to a larger view by clicking on the image. In all of the graphics, a rank of 1 indicates the highest flow of all years analyzed. Rankings of streamflow are grouped into much-below normal, below normal, normal, above normal, and much-above normal, based on percentiles of flow (greater than 90 percent, 76–90 percent, 25–75 percent, 10–24 percent, and less than 10 percent, respectively) ( Some data used to produce maps and graphs are provisional and subject to change.

Publication Year 2016
Title Streamflow of 2015—Water year national summary
DOI 10.3133/fs20163055
Authors Xiaodong Jian, David M. Wolock, Harry F. Lins, Steve Brady
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Fact Sheet
Series Number 2016-3055
Index ID fs20163055
Record Source USGS Publications Warehouse
USGS Organization Kansas Water Science Center