The River Trail
ElevationAscent: 1,560' 476 m
Descent: -318' -97 m
High: 9,568' 2,916 m
Low: 8,043' 2,451 m
GradeAvg Grade: 5% (3°)
Max Grade: 20% (11°)
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“Roaring cascades, soaring cliffs, great campsites, and the easiest way to Thousand Island Lake.”— Lee Watts
You can drive to the trailhead in Agnew Meadows, if you arrive before 7 AM. You'll be charged $10 on exit, assuming you leave when the Minaret Road entrance station is open. If you arrive after 7 AM, you must take the shuttle bus. If you have exact change, tickets can be purchase from the driver for $7. Otherwise, they can be obtained from the Mammoth Mountain Visitor Center. The first bus leaves at 7:30 AM.
You cannot camp near the outlet of Thousand Island Lake. Campfires are not allowed at Thousand Island Lake or above 10,000 feet. They are allowed for most of the distance on the High Trail and the River Trail.
Shortly after the lake and about 2.5 miles from the start, pass the junction with the Shadow Creek Trail #614. The River Trail climbs up the east side of the canyon in two long switchbacks, because at this point the river gorge is too steep and narrow for a trail. You get only a partial view of this gorge, but a great view of Shadow Creek cascading 700 feet down from the Shadow Lake. At 4.4 miles, you'll near the river again and have good views of it most of the rest of the way. At 5 miles, we meet the junction with a trail that climbs steeply up to Agnew Pass and on to Clark Lakes.
At 5.4 miles there is a very large campsite where the stream from Garnet Lake finishes dropping through innumerable falls and cascades to join the San Joaquin River. This campsite is often used by runners and fishermen who have gear bought in by mule trains. It is an extremely beautiful campsite, but it is often crowded. There is an unmaintained and unsigned trail that climbs from here up to Garnet Lake. The trail is doable, but there is no bridge across the river. This crossing can be a very difficult and dangerous until after the snow melt.
The River Trail continues to climb staying fairly close to the water until it meets the High Trail at 6.5 miles. From there it is only another mile and 200 feet of climbing to reach Thousand Island Lake.
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