If you take highway 14 west towards Cameron Pass from Ft. Collins, you have a ton of options. Very few people take advantage of this area, and it is beautiful. Here are a few, check this out: http://www.resourceanalysis.com/trails/trail9/tr9.html http://www.resourceanalysis.com/trails/trail10/tr10.html
You can fish the Pouder all the way up to the pass.
It would take you an hour to an hour and a half, but this is high altitude so be careful. I have ran into snow in the middle of July before, so be prepared. Hope this helps out. Good Luck!!!
One thing to keep in mind with Buttonrock is that you do need to buy a seperate permit to fish there. It's around twelve dollars, and well worth it. You can get a permit through the City of Longmont's City Clerk's office.