The San Juan River headwaters start near Wolf Creek Pass.  Although this river has most of its shoreline located in Utah and New Mexico, the section that resides in Colorado runs right through the middle of Pagosa Springs.  You can fish the San Juan in the town of Pagosa Springs with a fishing permit, as long as you fish below the high watermark on private property through town.  Pagosa offers several parks and open spaces along the river making for easy access for fishing.