Recent studies have suggested that there are more then 15,000 fish per mile..
Located in the northwest corner of New Mexico, the San Juan River is world renowned for providing some of the most rewarding trout fishing you will ever experience. The San Juan is a consistent producer of both rainbows and browns averaging 16 to 18 inches, with many reaching much larger proportions.
The San Juan River is a significant tributary of the Colorado River in the southwestern United States, about 383 miles (616 km) long. The river drains an area of about 24,600 square miles (64,000 km2) in southwestern Colorado, northwestern New Mexico, southeastern Utah, and a small part of northeastern Arizona. The average flow of the San Juan River at Bluff is about 2,200 cubic feet per second (62 m3/s) and the highest discharge ever measured was about 70,000 cubic feet per second (2,000 m3/s) on September 10, 1927.
The San Juan River joins the Colorado River at Lake Powell, a huge reservoir, and in fact the westmost (and lowest) miles of the San Juan River are impounded by Lake Powell and the Glen Canyon Dam. Most of the San Juan River lies in San Juan County, New Mexico and San Juan County, Utah, which share a boundary of one point at the Four Corners. The San Juan River lies just a few miles northeast of the Four Corners point.