This is an Add-In for the ArcGIS ArcMap software that allows for basic and advanced analysis of river systems.  It leverages and extends upon the existing network analysis functions and methods of ArcGIS, using the 'Geometric Network' model.  This toolset was developed by Fisheries & Oceans, Canada (2006-2010) and made public (2011) under a Canadian Creative Commons Canada Attribution Sharealike License.