The San Juan River in far southeastern Utah is floatable for rafts, canoes and kayaks for roughly 100 miles. The runnable sections of the river begin in the open San Juan valley east of Bluff, leading through stretches of sandstone bluffs, and then into spectacular, deep canyons, finally ending in Lake Powell. The river is divided into three segments, and it is open to private boaters with a BLM permit-lottery system. Commercial outfitters also offer trips on the San Juan.
Along the way, boaters will experience mild to moderate rapids, stretches of riffles or flat water, and high cliffs of desert-varnished sandstone. Further on, the river cuts deep "gooseneck" bends through layer after layer of sedimentary rock before the walls drop lower as boaters approach the San Juan Arm of Lake Powell.
Along the river can be found a number of scattered ancient Anasazi/Puebloan rock art sites. Primarily these are petroglyph panels, but a few pictographs may be found. There are also a few ruin sites - granaries or dwellings. All cultural sites and artifacts are protected by law. Sites on the south bank of the San Juan are on Navajo lands, requiring a separate hiking permit.
Boaters can find campsites widely scattered along the valley riverbanks, and further downriver, at side canyons or rapids. Some stretches of this river can be done as day trips, but the lower run down to the lake is a multi-day float.
The San Juan River runs just north of Monument Valley and cuts its deepest canyon below Utah's Cedar Mesa where it flows 6.5 miles through the Goosenecks of the San Juan while advancing only 1.5 miles toward Lake Powell. This river is unique for its remote nature, deeply-incised Goosenecks in the lower stretches of sedimentary rock, prehistoric cultural artifacts, and remnants of historic settlement. Below the Goosenecks are Johns, Slickhorn, and Grand Gulch canyons all of which offer interesting day hikes from the river.
The river is runnable year-round, although winter weather can be a challenge. Spring and fall are the best seasons, depending on snowmelt, with high water in late May. Monsoon season rains, generally in July and August, can also raise water levels, sometimes in a hurry. On the plus side, summer rains produce many small waterfalls off the cliffs and from the side canyons.
The river alternates from upper sections of flat water and riffles to Class II and III rapids in the canyon segments. Several named rapids at major side canyons have created the larger rapids, which are rated depending on the water level at the time. These include Eight-Foot and Ledge Rapids in the upper section, and Government and Slickhorn Rapids in the lower stretch. Note that sandbars can develop in the last few miles down to Lake Powell, as the current slows noticeably, depending on lake level, as the river leaves the canyon.
While one generally cannot get lost on a river, the first-time boater here should have and extensively study a San Juan river guidebook. The BLM website (blm.gov/ut) also covers the basics of the experience in detail. The rapids are not extreme, but knowing what lies ahead, and possible campsites or attractions, also suggests having some in the group who have run the San Juan before.