StreamStats Version 4.30.0 released
StreamStats version 4.30.0, released on December 12, 2025, uses all new services that were built with open-source software components. These services perform the work behind the StreamStats application to delineate basins and compute basin characteristics, which are used to estimate streamflow statistics.
Because of this transition to open-source components, you may see small differences in computed results compared to those from the previous versions. These differences are expected and do not reflect errors in the underlying data or analytical methods. Please take these changes into account when reviewing outputs or comparing results generated before and after the update. If you have any questions or concerns, contact the StreamStats Team at streamstats@usgs.gov. During the transition to open-source services, updates also were implemented to background data for several states in StreamStats. Detailed information for affected states is listed here.
The open-source code development revised the longest flow path method to follow the longest flow path upstream until the path finds the most upstream stream grid cell. From that cell, the longest flow path switches to a slope-based, least-cost method to define the flow path from the most upstream stream grid cell to the basin edge. Thus, the longest flow paths and derivative basin characteristics will have differences. In most cases, where the longest flow paths did not diverge between methods, the resulting derivative basin characteristics have minor differences; however, in some cases a completely different longest path was determined using the revised method which results in larger differences in derivative basin characteristics. For this longest flow path to be performant, a longest flow path vector network was created for each of the following state applications using open-source code.
- Arkansas
- Colorado
- Connecticut
- Hawaii
- Louisiana
- Massachusetts
- Minnesota
- Mississippi
- Missouri
- New Jersey
- New York (length of the Main Channel)
- North Carolina
- North Dakota
- Ohio
- Puerto Rico
- Rhode Island
- South Carolina
- South Dakota
- Wisconsin
Alaska:
The stream grid and data layers for Hydrologic Unit Code (HUC) 19020302 were updated and released in the January 24, 2025, migration.
Arkansas:
Data layers used for delineation in HUC 08040202 were corrupted and resulted in incorrect delineations in some locations. These layers were reprocessed and implemented in the August 1, 2025, migration.
Idaho:
HUCs 17010101, 17010102, 17010103, 17010104, 17010105, 17010106, 17010215 were shifted from the rest of the data in StreamStats and many of the basin characteristics computed for these HUCs are incorrect. An exclusion polygon was added to these HUCs to advise users of potential errors.
Iowa:
The stream grid used in Iowa had discontinuities between 8-digit HUC (HUC8) boundaries and therefore a new stream grid was created and implemented for Iowa. In most cases there will be no differences between the current and previous versions of the stream grid and will only be noticed at HUC8 boundaries.
Mississippi:
LC11DINT is a derived basin characteristic compiled using additional land cover characteristics. Errors in the equation for compiling LC11DINT were resolved.
New Jersey:
The stream grid raster was replaced for 10-digit HUC 0204010405, as it was resulting in incorrect delineations for user click points.
New York:
- The stream grid layer in HUC 02010001 was updated on the client to match the stream grid layers used for delineation.
- Delineation inside of Lake Champlain was disabled to prevent users from using incorrect delineations.
Oklahoma:
- A corrupted elevation raster for HUC 11040001 was replaced.
- Exclusion polygons were added to streams where large upstream delineations originate from out of state and may not be correct as these areas were not processed for the Oklahoma application. These exclusion polygons were implemented in the May 16, 2025, migration.
South Dakota:
Data for HUC 10140201 were corrupted and resulted in incorrect delineations in some locations. These layers were reprocessed and implemented in the May 15, 2025, migration.
Utah:
Vector and raster data used to represent stream locations were replaced in HUC 14080201.
Wisconsin:
Flow direction rasters and corresponding stream rasters were incorrect for multiple locations in Wisconsin resulting in incorrect delineations and computation of variables used in StreamStats. These layers were edited to resolve those issues and used to determine a new longest flow path vector layer.
Wyoming:
For some basins in Wyoming, the delineations were incorrect, and an exclusion polygon was implemented in the April 4, 2025, migration, to prevent delineations in these areas. These data have been fixed, and the exclusion polygons have been removed, allowing users to get correct delineations in these areas.