Documentation on the analysis software that is part of the CWMS system, such as HEC-HMS, HEC-ResSim, HEC-RAS, and HEC-FIA are available on HEC's website:
http://www.hec.usace.army.mil/
.
However, CWMS Version 3.1.1 may include versions of the analysis software that have not been released to the public. For those, version-specific documentation is available from HEC upon request.