Although many of the US Forest Service web sites have had the frequency data for the radio systems scrubbed from the available documents, occasionally some still get posted.
If you are interested in frequencies used by Colville National Forest in Washington State, you can find this document on their web site, at least for the time being:
http://www.fs.fed.us/r6/colville/newicc/documents/Colville2009_Radio_UserGuide.pdf