Version History
(Note: Database changes are listed in black. Program changes are listed in blue.)
NSS/StreamStats database update  20160425  This version of the database modifies SIR 20065306 Navajo flood regions 8 and 11 for AZ, CO, and UT to use basin slope in ft/ft instead of basin slope in percent, matching identical changes made to NM in the 20160420 database version.
NSS/StreamStats database update  20160420  This version of the database adds many new features and corrections as described below:
 New peakflow equations:
 Montana (SIR 20155019)
 Alaska (SIR 20165024)
 Maine (SIR 20155049)
 New low/mean/durationflow equations:
 Montana (SIR 20155019)
 Illinois (SIR 20145177)
 Indiana (SIR 20145177)
 Maine (SIR 20155151)
 Minnesota (SIR 20155170)
 Corrections:
 All equations in New Mexico from SIR 20085119, WRIR 014271, and SIR 20065306 using BSLDEM30M were modified to use BSLDEM30ff instead.
 Region names for Alaska peak flow equations were modified.
 Equations from Arizona SIR 20145211 were modified to use Contributing_Drainage_Area instead of Drainage_Area.
 Region names were modified for zeroflow probability equations in Iowa (SIR 20125171).
 Corrected errors in 7Q2 and 7Q10 equations for May in region 3 for Oregon.
 Corrected TAU* parameters in Arkansas (SIR 20085065) to use units of days, not years.
 Changed slope units for lowflow statewide equations to match correct units from report (SIR 200450322).
 Expired ROI equations from North Carolina removed from database.
NSS/StreamStats database update  20151013  This version of the database replaces peak flow equations for North Dakota (SIR 20155096) and adds singlevariable peakflow equations for Oklahoma Panhandle (SIR 20155134).
NSS/StreamStats database update  20150929  This version of the database adds new singlevariable peakflow equations for Iowa (SIR 20155055), adjusts prediction error values for Rhode Island peak flow equations, corrects errors in Iowa's Low_Flow_Southern_Region_2012_5171 equations, and corrects errors in Oregon lowflow equations.
NSS/StreamStats database update  20150612  This version of the database adds new lowflow equations from Arkansas (SIR 20155031) and makes minor adjustments to Rhode Island peakflow equations (SIR 20125109).
NSS/StreamStats database update  20150226  This version of the database adds groundwater recharge equations for New Hampshire (SIR 20045090), lowflow equations for New York (SIR 20105063) and Arizona (SIR 20145109), rural peak equations for Arizona (SIR 20145211), and urban peak equations for Virginia (SIR 20145090). Maine peak flow equations for D50, QA, and MARD50 are corrected. Minor errors not affecting streamflow computations were corrected for Kentucky and South Dakota.
NSS/StreamStats database update  20141007  This version of the database adds new peak equations from Missouri and new lowflow equations from Missouri and West Virginia. Kansas lowflow equations from SIR 20045032 were modified to prevent them from producing negative values at low flows. Minor errors not affecting streamflow computations were corrected for Tennessee, Georgia, North Carolina, South Carolina, and South Dakota.
NSS Program update: Version 6.1  20140923  This version of the program adds a number of new features. Report citations and html links are now displayed in the Edit Scenario window, allowing the user to quickly jump to the USGS report detailing the development and use for the selected equation set (region). The Edit Scenario window now warns the user when it has rounded input variables prior to computation. "Probability of Zero Flow" estimates are now reported with "Percent Correct" indicating what portion of stations in the study are accurately predicted by these equations.
NSS/StreamStats database update  20140806  This version of the database adds new peak equations from Vermont and new lowflow equations from Maine. Minor errors not affecting streamflow computations were corrected for New Hampshire and Kentucky.
NSS/StreamStats database update  20140612  This version of the database corrects errors in streamflow estimates encountered in the 20140509 version of the database for the States of Florida, Iowa, Ohio, Pennsylvania, Tennessee, and Utah. For more details, please see the Known Issues link on the NSS software download page.
NSS/StreamStats database update  20140509  This version of the database adds new peak urban streamflow equations for Georgia, North Carolina, and South Carolina. Bankfull equations are added for Kentucky, Massachusetts, and Maine. Nonpeak streamflow equations are added for Kentucky, New Jersey, and Rhode Island. Standard errors of prediction are updated for Colorado nonpeak equations. Kansas nonpeak equations are updated to include previously unsupported subtracted terms.
NSS/StreamStats database update  20130828  This version of the database adds new peak streamflow equations for Iowa and West Virginia and adds new nonpeak streamflow equations for Indiana, Iowa, and Pennsylvania. It corrects peak flow equations in Georgia and North Carolina. It also corrects errors in nonpeak equations in Arkansas, Ohio, Oregon, and Vermont and copies Maryland nonpeak equations to Delaware.
NSS/StreamStats database update  20121121  This version of the database renames peak urban stats in Alabama, adds Standard Error of Prediction to Missouri Urban equations, and adds new peak streamflow equations for California, Florida, Rhode Island, and Virginia. It also adds new urban peakflow equations for Georgia and lowflow equations for Iowa, Ohio, Virginia, and Washington.
NSS Program update: Version 6.0  20120803  Adds a 64bit Windows OS compatible installer, brings the flowtype selection to the NSS main screen, adds proper display of Standard errors and prediction intervals for urban scenarios, and improves results display format.
NSS/StreamStats database update  20120509  This version of the database prevents negative lowflow results in Oregon, corrects errors in Region 7 peak flow prediction intervals in Illinois, removes outdated ROI equations from North Carolina, renames TAU_x variables in Arkansas, corrects BCF for New York bankfull equations, presents newer ROI routines for Tennessee, and corrects errors in Maryland lowflow equations.
NSS/StreamStats database update  20110324  This version of the database adds new urban peak flow equations for Alabama, adds prediction intervals to Arkansas peak flow equations, and adds new lowflow equations for Kentucky. Corrections for lowflow equations from Utah SIR 20085230 were entered into this database, and the PK25 covariance matrix was corrected for Puerto Rico. This database should be used with NSS program version 5.1.2 as posted.
NSS/StreamStats database update  20110204  This version of the database corrects mislabeled units in Maryland peak flow equations from AHMMD 2010 and corrects mislabeled units in Texas peak flow equations from SIR 20095087. This database should be used with NSS program version 5.1.2 as posted.
NSS/StreamStats database update  20110118  This version of the database adds new peakflow equations for Maryland, Oklahoma, and Texas. New urban peakflow equations were added for Missouri, and new lowflow equations were added for Alaska. This database should be used with NSS program version 5.1.2 as posted.
NSS/StreamStats database update  20101115  This version of the database adds new lowflow or flowduration equations for Oregon, Arkansas, Tennessee, New York, Hawaii, Washington, and Ohio. Arkansas regionofinfluence (ROI) equationswere removed. Errors were corrected in nonpeakflow equations for Maryland and peakflow equations for Hawaii, Maine and Nevada. Prediction interval calculations were added for New Hampshire. This database should be used with NSS program version 5.1.2 as posted.
NSS Program update: Version 5.1.2  20101115  Adds the ability to filter equations by one of three types: "Peak", "Probability" (of zero flow), and "Other" (nonpeak). Please go to File...Options within the program to select a flow type before using the program. Also adds the ability to display peak flow statistics with traditional recurrence interval labels or newer percent chance exceedance labels (e.g. "PK100" vs. "1% flood").
NSS/StreamStats database update  20100726  This version of the database corrects an error in Region 3 equations for Wisconsin. Peakflow and lowflow equations in New Hampshire are updated with prediction interval computation. New peak equations for Hawaii are updated to coincide with recent revisions. This database should be used with NSS program version 5.1 as posted. There are no changes to the program version 5.1.
NSS/StreamStats database update  20100621  This version of the database adds new peakflow equations for Colorado, Georgia, Hawaii, Minnesota, North Carolina, New Jersey, Oklahoma, and South Carolina. New duration equations are added for Connecticut and Oklahoma. Equation errors are corrected for mean flow equations in Ohio. This database should be used with NSS program version 5.1 as posted.
NSS Program update: Version 5.1  20100621  Added the ability to solve a wider range of regression equations and to weight streamflow estimates by variance. Added new functionality that will eventually result in being able to describe streamflows in terms of annual exceedance probabilities or recurrence intervals. Identified and corrected a problem with prediction interval computations.
NSS/StreamStats database update  20090720  This version of the database adds peak flow equations from New Hampshire report SIR 20085206. It also includes missing PK500 estimates for Alabama and Hawaii that were mistakenly deleted in previous versions and also includes minor modifications to equations from Kentucky report WRIR 914097. This database should be used with NSS program version 4.0b as posted. There are no changes to the NSS program version 4.0b.
NSS/StreamStats database update  20090408  This version of the database adds peakflow equations for West Virginia and Oklahoma and lowflow equations for Kentucky, Utah, and West Virginia. This database should be used with NSS program version 4.0b as posted. There are no changes to the NSS program version 4.0b.
NSS/StreamStats database update  20090227  There are no changes to the NSS program version 4.0b. This version of the database adds peakflow equations for New Mexico and corrects some error statistics in Florida. This database should be used with NSS program version 4.0b as posted.
NSS/StreamStats database update  20090127  There are no changes to the NSS program version 4.0b. This version of the database adds peakflow equations for Arkansas, South Carolina, and Florida. It also adds urban peak equations for New York and updates urban equations for North Carolina's Blue Ridge and Piedmont regions. This database should be used with NSS program version 4.0b as posted.
NSS Program update: Version 4.0b  2008/12/08  Added the abilities to (1) handle regression equations that have a multiple explanatory variables in the exponent term; (2) incorporate logistic regression equations that are found in some lowflow reports (ie the chance of a stream having zero flow); and (3) enable computing of areaweighted prediction intervals for sites with drainage area in more than one hydrologic region. In addition there was some cleanup in the way regression equations were presented in the output report.
New peakflow equations have been added for Alabama, Arizona, Colorado, Florida, Louisiana, New Mexico, New York, Pennsylvania, South Carolina, and Utah, including completion of Utah Region_4. New lowflow equations have been added for Florida, Hawaii, Idaho, Montana, and Tennessee. Minor corrections were made to existing equations for Alabama, Delaware, Idaho, Illinois, Indiana, Texas, and Utah, including adding the ability to do prediction intervals for Indiana flood frequency estimates.
NSS Program update: Version 4.0  2006/12/01  Added the abilities to (1) solve regression equations for all types of streamflow statistics, not just floodfrequency statistics, (2) use regionofinfluence regression for states where it is implemented, (3) compute 90percent prediction intervals for estimates where methods for computing them are documented in reports.
NSS Program update: Version 4.0 – 2006/12/01  Added the abilities to (1) solve regression equations for all types of streamflow statistics, not just floodfrequency statistics, (2) use regionofinfluence regression for states where it is implemented, (3) compute 90percent prediction intervals for estimates where methods for computing them are documented in reports.
National Flood Frequency program (NFF) Version 3.2  2004/12/14  Updated the database to NFFv3.2_20041214.mdb. Added new peakflow equations for Connecticut and Kentucky. Corrected an error in the units displayed for conveyance in the Houston urban equations from in/hr to cubic feet per second. Corrected an error in the Wisconsin Area 1 equation for the 5year recurrence interval.
National Flood Frequency program (NFF) Version 3.2  2004/12/14  Updated the database to NFFv3.2_20041214.mdb. Added new peakflow equations for Connecticut and Kentucky. Corrected an error in the units displayed for conveyance in the Houston urban equations from in/hr to cubic feet per second. Corrected an error in the Wisconsin Area 1 equation for the 5year recurrence interval.
NFF Version 3.2  2004/09/29  Updated the database to NFFv3.2_20040929.mdb. This database contains new peakflow equations for Alaska, Idaho, Ohio, Tennessee, Vermont, Wisconsin, and Wyoming. Along with the new database comes the ability to display 90percent prediction intervals with the estimates for some of the updated States.
NFF Version 3.2 – 2003/04/30  Fixed a bug in the weighting routine that occurred when equivalent years of record were missing for the regression estimates, and a bug that occurred when the drainage area for an ungaged site was in more than one region and the regions had different sets of return intervals.
NFF Version 3.1.1  2003/03/28  Fixed a bug in the weighting routine that was introduced in the version 3.1 update.
NFF Version 3.1  2003/02/27  Fixed a problem with solving the national urban equations that occurred when one or more of the local rural equations were missing for the region of interest. If a rural equation, such as the 5year flow, was missing NFF would use the flow estimate for the next available recurrence interval, such as the 10year flow, to estimate the urban flow for the missing recurrence interval. All estimates for higher recurrence intervals would also be incorrect.
NFF Version 3.0  2002/10/15  Major change in converting user interface from Microsoft DOS to Microsoft Windows and converting data base from a binary file to Microsoft Access (Note: Use of trade or product names is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey). Updates or corrections to equations for


NFF Version 2.0  1996/09/15  A nonUSGS release that added conversions between English and metric units.
NFF Version 1.4  1996/09/30  NFF data base updated to amend incorrect values for:
 New Jerseythe constant 1 was removed from being added to the actual value entered for impervious cover, I
 New Yorkincorrect exponents and an incorrect regression constant were corrected for Region 6's 25year and 500year equations, respectively
 Wisconsinthe constant 2.3 was added to the data base to be applied automatically to the actual value entered for 2year 24hour rainfall, INTENS, for Areas 1, 3, and 5; incorrect exponents were corrected for Area 3's 5, 25, 50, and 100year equations
NFF Version 1.3  1996/02/14  Corrected labeling of floodfrequency recurrence intervals for North Dakota. The equations developed for North Dakota are for the 2, 10, 15, 25, 50, 100, and 500year recurrence intervals rather than the standard 2, 5, 10, 25, 50, 100, and 500year intervals.
NFF Version 1.2  1995/06/02  NFF data base updated to amend incorrect exponents in West Virginia's Region 6 equations for the 2year and 10year recurrence interval.
NFF Version 1.1  1994/11/21  Initial release.