The password for the Arc Hydro ftp site changed on 10/1/2013, and will be reset every 6 months. The current password is ADSRiver.2013b.
Future passwords will be posted on the Arc Hydro Forum, and also on the Hydro Blog. The forum features discussions on Arc Hydro for ArcGIS 10.2, information about tutorials and documentation, and opportunities to to reach out to the community for help. The Arc Hydro forum is also a way for the Esri Arc Hydro team to recognize what problems users are encountering, and work to solve these bugs in the next release of the Arc Hydro tools. Get involved in the Arc Hydro community via the Arc Hydro Forum!