StreamStats, Version 4

Introduction

StreamStats version 4, available at https://streamstats.usgs.gov, 

is a map-based web application (fig. 1) 

that provides an assortment of analytical 

tools that are useful for water-resources 

planning and management, and engineering purposes. Developed by the U.S. 

Geological Survey (USGS), the primary 

purpose of StreamStats is to provide estimates of streamflow statistics for userselected ungaged sites on streams and for 

USGS streamgages, which are locations 

where streamflow data are collected.

Streamflow statistics, such as the 

1-percent flood, the mean flow, and the 

7-day 10-year low flow, are used by 

engineers, land managers, biologists, 

and many others to help guide decisions 

in their everyday work. For example, 

estimates of the 1-percent flood (which is 

exceeded, on average, once in 100 years 

and has a 1-percent chance of exceedance 

in any year) are used to create flood-plain 

maps that form the basis for setting 

insurance rates and land-use zoning. This 

and other streamflow statistics also are 

used for dam, bridge, and culvert design; 

water-supply planning and management; 

permitting of water withdrawals and 

wastewater and industrial discharges; 

hydropower facility design and regulation; and setting of minimum allowed 

streamflows to protect freshwater 

ecosystems. Streamflow statistics can be 

computed from available data at USGS 

streamgages depending on the type of 

data collected at the stations. Most often, 

however, streamflow statistics are needed 

at ungaged sites, where no streamflow 

data are available to determine the 

statistics.

Sidebar

Map Frame

Exploration Tools Map Layers/Legend

Zoom In/Out

Exploration Tools Layers

StreamStats

StreamStats 4.0

SELECT A STATE / REGION

Secure https://streamstats.usgs.gov/ss

Figure 1. View of the StreamStats version 4 user interface at initiation.

U.S. Department of the Interior

U.S. Geological Survey Printed on recycled paper Fact Sheet 2017–3046October 2017

Supersedes USGS Fact Sheet 2008–3067
Functionality

Ries and others (2004, 2008) 

described the development, functionality, 

and limitations for use of previous 

versions of StreamStats. Currently 

(2017), StreamStats version 4 includes 

Geographic Information System (GIS)-

based tools that allow users to delineate 

drainage-basin boundaries for userselected sites, compute a variety of basin 

characteristics, and estimate streamflow 

statistics for the selected site. StreamStats 

can perform these analyses much faster 

than historically used manual techniques. 

In addition, users can obtain descriptive 

information as well as previously published basin characteristics and streamflow statistics for USGS streamflow 

streamgages. These tools can be accessed 

through a map-based user interface that 

appears in the user’s web browser 

(fig. 1), or individual tools can be 

accessed as web services by other web or 

desktop computer applications.

StreamStats includes additional tools 

that allow editing of delineated basin 

boundaries, and computing distances and 

elevation profiles between selected points 

on the map. Custom tools are available 

for some states. For example, tests for 

the presence of upstream regulation from 

dams are available for Colorado and 

Montana, and summaries of water withdrawals and discharges can be obtained 

for delineated basins in the Delaware 

River Basin and in northeastern Ohio. 

Several new tools that rely on navigation 

along the digital stream network are in 

development.

Web Site

The StreamStats home page provides a brief description of the application and some disclaimers about using 

it. The page also includes links to News, 

Documentation, How it Works, Web 

Services, Batch Tool, and Help pages. 

The News page provides information 

on changes to StreamStats, such as the 

addition of new states or methods for 

estimating streamflow statistics, operational problems, and anticipated disruptions of service. The Documentation page 

provides links to definitions of basin 

characteristics and streamflow statistics 

that appear in StreamStats outputs, this 

Fact Sheet, a users’ manual, presentations 

and articles on StreamStats, and USGS 

internal resources. The How it Works

page describes the functionality that is 

available, how it works, the development 

strategy, outputs, and the StreamStats 

development team. The Web Services and 

Batch Tool pages describe how to use 

the StreamStats web services and batch 

tool, and provide access to those capabilities. The Help page provides information 

on how to obtain support for using 

StreamStats.

StreamStats User Interface

The StreamStats version 4 user 

interface (fig. 1) can display a variety 

of base maps and allows users to locate, 

select, and obtain information for gaged 

and ungaged sites of interest. The largest 

part of the interface consists of the 

Map Frame, which displays default and 

optional digital map layers, and allows 

the selection of sites of interest. In the 

top left corner of the Map Frame is the 

Exploration Tools button, and at the top 

right is the Layers button. Clicking on 

the Exploration Tools button reveals 

additional buttons for querying information for streamgages, measuring distances 

and obtaining elevation profiles between 

user-selected locations on the map, and 

showing your current location on the 

map. Clicking on the Layers button 

reveals buttons that allow turning on and 

off the digital map layers and defines the 

symbols that are shown for each layer. 

Below the Exploration Tools button 

are the Zoom In and Out plus (+) and 

minus (-) buttons that allow making the 

scale of the map larger or smaller, respectively. The current scale and map zoom 

level are shown in a small text box at the 

lower left of the Map Frame.

The Sidebar (fig. 2), to the left of the 

map, is used primarily to zoom quickly 

to sites of interest and to obtain information for user-selected ungaged sites. The 

Sidebar presents a series of banners that, 

when selected, will turn from gray to 

blue and expose a panel of tool buttons 

and instructions on how to use them. The 

Select a State/Region banner at the top is 

activated initially, and contains a search 

tool that allows entering information 

about a location, such as an address, a zip 

code, or a state, zooming the map to that 

location, and selecting the state in which 

the site is located. When users complete 

using the tools under one banner, the 

next banner will activate automatically 

and expose its tools. The Identify a Study

Figure 2. View of the StreamStats 

sidebar with the Select Scenarios banner 

activated and buttons for choosing the 

types of streamflow statistics and basin 

characteristics to be obtained.

Area banner allows delineating the drainage basin for a selected site, editing the 

delineated basin, and downloading the 

basin in a variety of formats that can 

be read by GIS applications. The Select 

Scenarios banner allows selection of the 

types of statistics to be estimated for the 

site based on regression equations, and 

the basin characteristics to be computed. 

The Build a Report banner allows selection of whether to include summaries of 

streamflow statistics, basin characteristics, or both, in the output report. The 

resulting report can then be printed, saved 
to a machine-readable file, or exported 

with the delineated basin in a variety of 

GIS formats.

The Help, About, and Report links 

appear toward the right side of the black 

banner above the Map Frame. The Help

link opens a page that provides access 

to the users’ manual, a list of frequently 

asked questions and answers, and a form 

for submitting requests for support to 

the StreamStats development team. The 

About link opens a page that provides 

a very brief description of StreamStats, 

detailed information about the selected 

state or river basin, and news items about 

changes or upcoming events that may 

be of interest to users. Clicking on the 

Report link will cause StreamStats to 

generate a report that shows the results 

from whatever tools have been used up to 

the point at which the link was clicked.

This Fact Sheet does not fully 

describe how to use StreamStats. 

Complete documentation can be accessed 

through the links provided on the 

StreamStats home page and through 

the Help link on the user interface. It is 

highly recommended that users read the 

program documentation before attempting to use StreamStats. In particular, 

users who wish to estimate streamflow 

statistics for ungaged sites should review 

the information on the State/Regional

Info tab that can be accessed from the 

Help link after selecting a state or region 

and the reports that are listed on the tab.

Information for Streamgages

Nearly 500,000 basin characteristics 

and 1.5 million streamflow statistics are 

available from StreamStats for more than 

36,000 USGS streamgages nationwide. 

About 8,500 of the stations are currently 

operating streamgages where data are collected on a continuous basis, and about 

12,000 of them are streamgages where 

data collection has been discontinued. 

Other station types include partial-record 

stations, and miscellaneous-measurement 

stations. Streamflow measurements are 

collected systematically over a period of 

years at partial-record stations to estimate 

peak-flow or low-flow statistics, or both. 

Streamflow measurements usually are 

collected at miscellaneous-measurement 

stations for specific hydrologic studies 

with various objectives. The station locations are displayed on the StreamStats 

Map Frame as various colored triangles 

to indicate the station type. Simply clicking or tapping on a streamgage symbol on 

the map provides access to the available information, including descriptive 

information, basin characteristics, and 

streamflow statistics. 

Available information varies among 

stations depending on the type of data 

collected at the station and the interests of 

local cooperating agencies who may have 

shared in the cost of computing the statistics. Descriptive information includes: 

the USGS station number, station name, 

station type, period of record, latitude, 

longitude, hydrologic unit code, county, 

directions to locate the station, and 

remarks indicating any effects of human 

impacts or other pertinent information 

about the station. All basin characteristics and streamflow statistics provided 

by StreamStats for USGS stations were 

previously computed and citations are 

provided for each value. More than 850 

different types of basin characteristics 

and more than 2,650 different types of 

streamflow statistics are available for 

the stations, although individual stations 

usually have only a small number of them 

available.

Streamflow Statistics for Ungaged 

Sites

StreamStats relies on regional 

regression equations that were mostly 

developed and published by the USGS to 

estimate streamflow statistics for ungaged 

sites. Regression equations are developed 

by statistically relating the streamflow 

statistics to the basin characteristics for 

a group of streamgages within a region. 

Estimates of streamflow statistics for 

an ungaged site can then be obtained by 

measuring its basin characteristics and 

inserting them into the regression 

equations (see inset).

The tools provided in the 

StreamStats Sidebar automate the process 

for users to (1) locate their ungaged 

site of interest in the user interface, (2) 

delineate the drainage basin, (3) compute 

basin characteristics, (4) estimate flow 

statistics, and (5) produce an output 

report that provides a map of the delineated basin and summarizes the available 

information for the site. Depending on 

the size of the basin and the types of 

basin characteristics measured, this automated process can save from an hour to 

a few days of work, compared to efforts 

needed to do the work manually.

StreamStats delineates the drainagebasin boundary for a selected site by use 

of an evenly spaced grid of land-surface 

elevations, known as a Digital Elevation 

Model (DEM), and a digital representation of the stream network. When a user 

selects a site along the digital stream 

network, the site location is transferred 

to a point in the DEM, and the DEM 

is then used to determine the drainage 

boundary. The DEM for most states has 

been enhanced by a process that ensures 

conformance to the stream network 

and a dataset of pre-existing drainage 

Regression Equations

Reference

The USGS has developed equations to

estimate peak-flow frequency statistics,

such as the 100-year flood, for ungaged

sites in every state. Regression equations

also have been developed to estimate

other types of streamflow statistics for

many states. As an example, the equation

for estimating the 100-year flood for

ungaged sites in Vermont is

100

PK = 0.251 DA (S+1) 100 P 0.854 -0.297 1.089

where

PK

DA

S

P

is the peak flow that occurs, on

average, once in 100 years

(1-percent change of occurrence

in any year), in cubic feet per

second;

is the drainage area, in square

miles;

is the percent of the basin

covered by wetlands and water

(storage); and

is the mean annual precipitation,

in inches.

Olson, S.A., 2014, Estimation of flood

discharges at selected annual

exceedance probabilities for

unregulated, rural streams in Vermont,

with a section on Vermont regional

skew regression, by Veilleux, A.G.:

U.S. Geological Survey Scientific

Investigations Report 2014–5078,

27 p. plus appendixes, accessed

May 18, 2017, at

http://dx.doi.org/10.3133/sir20145078.
boundaries. This enhancement results in 

delineations that usually are of greater 

accuracy than delineations obtained from 

a standard DEM.

StreamStats version 2 previously 

included a tool that also was able to 

estimate streamflow statistics for ungaged 

sites on the basis of the flow per unit 

area at an upstream or downstream 

streamgage. That functionality is being 

redeveloped for version 4 and will be 

documented in the users’ manual when it 

becomes available.

Limitations for Ungaged Site 

Estimates

StreamStats processes rely on the 

use of very large, complex datasets. 

These datasets mostly were developed by 

other entities internal and external to the 

USGS, and can contain occasional errors. 

Users are advised to carefully check all 

results for accuracy and to exercise their 

own professional judgment in evaluating 

the appropriateness of the results for 

their application. Basin delineations, in 

particular, can be erroneous. The web 

site provides tools and base maps useful 

for verifying the accuracy of the basin 

delineations and editing them.

Estimates of streamflow statistics 

that are obtained from regression equations are based on the assumption of 

natural flow conditions at the ungaged 

site unless the reports that document 

the equations state otherwise. If human 

activities such as dam regulation and 

water withdrawals substantially affect the 

timing, magnitude, or duration of flows 

at a selected site, the regression-equation 

estimates provided by StreamStats should 

be adjusted by the user to account for 

those activities.

StreamStats can be used to obtain 

estimates of streamflow statistics for 

USGS streamgages. Users should be 

aware that there are errors associated 

with estimates determined from available 

data for the stations as well as estimates 

determined from regression equations, 

and some disagreement between the two 

sets of estimates is expected. If the flows 

at the stations are affected by human 

activities, then users should not assume 

that the differences between the databased estimates and the regressionequation estimates are equivalent to the 

effects of human activities on streamflow 

at the stations.

In addition to estimates of streamflow statistics, StreamStats outputs for 

ungaged sites include indicators of the 

errors associated with the estimates, as 

well as values of the basin characteristics 

that are used as explanatory variables 

in the equations and the minimum and 

maximum values of those basin characteristics for the streamgages that were 

used to develop the equations. When 

one or more of the basin characteristics 

for an ungaged site are outside the given 

ranges, then the estimates are extrapolated. StreamStats provides warnings 

when extrapolation occurs. Although 

StreamStats does provide estimates of 

streamflow statistics in these circumstances, no error indicators are provided 

with them, as the errors associated with 

these estimates are unknown and may be 

very large.

Web Services and Batch Tool

The Web Services and Batch Tool

links from the StreamStats home page 

provide access to instructions for using 

StreamStats web services and a batch 

tool, respectively. All StreamStats 

functionality is available as web services, 

meaning that other remote computer 

applications or web sites can initiate 

a request for a particular function 

over the Internet, and StreamStats can 

perform that function and deliver the 

result back to the remote application. As 

an example, an engineer could issue a 

request to obtain a basin delineation from 

StreamStats using a separate desktop 

mapping application and thus avoid the 

need to assemble and process the GIS 

data that would be needed in the desktop 

application to determine the delineation.

The batch tool produces shapefiles 

that contain the delineated basins, basin 

characteristics, and flow statistics for 

multiple sites requested at once. Users 

need to upload a shapefile of points of 

interest that have been edited in a GIS so 

they are coincident with the StreamStats 

stream grid before running the batch tool.

References Cited

Ries, K.G., III, Guthrie, J.D., Rea, A.H., 

Steeves, P.A., and Stewart, D.W., 2008, 

StreamStats: A water resources web 

application: U.S. Geological Survey 

Fact Sheet 2008–3067, 6 p., accessed 

May 18, 2017, at https://pubs.usgs.gov/

fs/2008/3067/.

Ries, K.G., III, Steeves, P.A., Coles, J.D., 

Rea, A.H., and Stewart, D.W., 2004, 

StreamStats: A U.S. Geological Survey 

web application for stream information: U.S. Geological Survey Fact 

Sheet FS 2004–3115, 4 p., accessed 

May 18, 2017, at https://pubs.usgs.gov/

fs/2004/3115/.

By Kernell G. Ries, III, 

Jeremy K. Newson, Martyn J. Smith, 

John D. Guthrie, Peter A. Steeves, 

Tana L. Haluska, Katharine R. Kolb, 

Ryan F. Thompson, Richard D. Santoro, 

and Hans W. Vraga

Additional Information

For more information, visit the 

StreamStats website at https://streamstats.

usgs.gov/.

ISSN 2327-6916 (print)

ISSN 2327-6932 (online)

https://doi.org/10.3133/fs20173046

Photographs by Edward J. Doheny, 

U.S. Geological Survey

Supersedes USGS Fact Sheet 2008–3067