I used to go up to the Encampment River in my younger days and really liked the place. Nice little medium sized river to fish. September should be perfect to fish anywhere in the area. You must go if you have the chance. It's a great neck of the woods.
Here's an outfit that has been there forever. Visit their website and give them a call on the 800 number. http://www.flystore.net/
Here's forewarning, you may just like it better than KS and wanna move there. GO WEST YOUNG MAN ! Bring your rod and gun. Just think... get up at 6 am KS time and 6pm, same day your in paradise.
"As far down the river as he could see, the trout were rising, making circles on the surface of the water, as though it were starting to rain."- E.H., The Big Two Hearted River