I have used a set of ESRI developed hydrology tools in the past and have a web app that uses them. There was Elevation Profile Generator, a Downstream Trace and a Watershed Basin tool.
Is there a help document somewhere that describes the process of using them in ArcGIS Online, that I can send someone a link to? They still work, I just used the profile generator. I don't think there was a special license to use the tools, like you have to have for Community Analyst, for example.
Thanks for any help.