Northeast of Durango, the Los Pinos River above Vallecito Reservoir is known for its rainbow trout, brook trout and cutthroats. A great place to start is Pine River Campground along the river. A trail heads northeast upstream along the river for about 3 miles to the Weminuche Wilderness Area boundary, and then it continues another 10 miles or so along the river to the headwaters.
To reach the Pine River Campground from Durango, head east on CR 240 (aka Florida Road) for roughly 16 miles to the town of Columbus. Turn left heading north on CR501 for roughly 5 miles to Vallecito Reservoir Dam. Turn right heading southeast on CR501A across the dam. Continue for 5 miles along the eastern shore. Turn right heading east on CR501 for 4 miles to the campground.
Overall, Los Pinos River is the 7th most popular fly fishing river of all 47 fly fishing spots in Colorado.