Smelter rapid at Santa Rita Park is the only class III rapid on the Lower Animas. It's the beginning of the whitewater park. The run through town is pretty fun though for an entertaining afternoon. River is running pretty low right now and not looking like it'll get much better, but should still be good for a run by next weekend. You can google Durango Parks and Rec for a map and guide to parks where you can put in and take out. Durango Colorado Official Web Site - Animas River
Trimble Bridge, about 8 miles noth of town is a private, but open to the public, put in for a 5 hour flatwater float. You also do not really want to float past River Road (AKA-Home Depot) as any access below there is private or tribal. I personally wouldn't float past the Wal-Mart/High Bridge take out right now.