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Water Resources of the United States

NSS Updates

Would you like to be notified when updates are made to the NSS program or new equations are added to the database?

Email Todd Koenig at to be added to the mailing list.

NSS, Version 6

National Streamflow Statistics program



NSS is a 2-part download consisting of a program installer and a password-protected database file which must be used together. See the README file for installation instructions.

Select both of the following links to retrieve the two distribution files required for a complete installation of NSS:

Software Downloads


NSS Program Installer: self-extracting executable of the NSS software (2,411,998 bytes, posted 2014-10-08). Please de-install any previous version of NSS and replace it with the most recent version before using the latest NSS database.


NSS Database: needed by NSS software (24,260,608 bytes). Previous version of the database was dated 2015-09-29. Note: This file is designed to be opened only by the NSS program. MS Access® is not required.

Please note: The database for NSS can change frequently as equations are added and updated. Please check this web site often to determine if a new version of the database is available. The version history link will document any changes made to the database or the software.

Region-of-Influence Data Files

Regional-of-Influence (ROI) is a method of developing custom regression equations for estimating streamflow statistics for individual ungaged sites. The method is described in the documentation provided below. One or two additional files need to be downloaded for each state and placed in the directory in which users have installed the NSS software and database to allow NSS to run ROI regressions.

Data Files






Documentation for Individual States

Point of contact for NSS:

Todd Koenig
U.S. Geological Survey
Office of Surface Water
1400 Independence Road, MS100
Rolla, MO 65401
(electronic mail:

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