Forest Service GPS Maps Page with links to local maps
The note on the Forest Service website is outdated — the Avenza PDF Maps app works on Android too.

If you have an I-Phone or I-Pad you can download these maps and then using the Avenza PDF maps App from I-Tunes you can use the GPS feature to track your location on these maps.  We hope this feature will be available to other smart phones soon.

For iPad, iPhone click me 

How to use QR codes on the Paper Maps:
A phone user may scan the QR Image directly into their phone using one of many free QR Scan Apps. Next the PDF Map App can be used to download the map file and connect to the map (refer to the FS Help Page).  This is an alternative to downloading the files through your home computer.