StreamStats version 2 had to be shut down on July 15, 2015 because the servers on which it ran used an obsolete operating system that was considered a security risk by the Department of Interior, of which the USGS is a part. Version 3 was placed in use before it was possible to develop code for all of the tools that were in version 3. Rather than continue to develop version 3, it was decided to put priority on replacing it with version 4, which feedback has indicated has a much improved user interface. After the initial release of beta version 4, emphasis is being placed on redeveloping the tools that were lost from version 2. It is planned to have all of the tools that were in version 2 operating in version 4 during 2016.