Those page that you are getting the message without an avast alert, I can only assume have been cleaned but the site I guess won't be available until they resolve not only the removal of the injected iframes but how they got there and to close that vulnerability.
So without URLs for those you can view without alert there is no way to confirm that they have in fact been cleaned. Though there is more than enough evidence that they have been hacked. If as you say this spreads over multiple sites, though I only see links for the one fs.fed.us domain it could be an orchestrated attack.
Sorry, here's a link to one of the "down" sites with an unavailable message
hxxp://www.fs.fed.us/r9/shawnee/
From viewing the source, it looks legit.
Your viewing of the source is different to mine as this too has most certainly been hacked (see image), with the same injection of a hidden iframe pointing to a Chinese domain...
So I don't see how you are able to see the page with the unavailable message, though that would also depend on your browser (?)