This past weekend, we backpacked to the breathtaking Thousand Island Lake in Ansel Adams Wilderness. We took the River Trail from Agnew Meadows and returned via the John Muir Trail to the Shadow Creek Trail. We logged 17.8 miles in total according to my GPS watch, an underestimate compared to GPS data from maps on AllTrails.
Initially, we planned to complete the trip over three days, but looming monsoonal storms encouraged us to cut the trip one day short.
Permits
Backcountry permit
Because Thousand Island Lake is in the Ansel Adams Wilderness, you need to secure a backcountry camping permit through Recreation.gov. Permits are available up to 6 months in advance of the date that you want to go. “Walk-up” permits, previously available physically at the ranger station, are now available online closer to the date of departure.
High Trail, Shadow Creek Trail, and River Trail all go to Thousand Island Lake. We decided to start on the River Trail because it offered more coverage than the High Trail.
California Campfire Permit
As with most backcountry areas, you need a California Campfire Permit for any open flame stoves (camp stoves). You can get this permit from Cal Fire.
Getting to River Trail Trailhead
The trail is at Agnew Meadows near Mammoth Mountain. The Reds Meadow/Devils Postpile mandatory shuttle runs from 7am-7pm during peak season. During that time, you are required to reach Agnew Meadow from the shuttle which departs from the Mammoth Mountain Inn. If you drive to Agnew Meadow outside of that time period, you do not need to take the shuttle.
The shuttle costs $15/adult or $7/child.
Whether you take the shuttle or arrive by car, proceed off Postpile/Red Meadow Road to Agnew Meadows. The first parking lot is where the High Trail trailhead is. The second parking lot is where the Shadow Creek and River Trail trailhead begins (they share the trailhead). If you see campsites, you went too far and are now in the Agnew Meadow campground. Turn back to the parking lots to find the trailheads.
Day 0: Drive to Mammoth and Car Camping
I try to avoid driving to a trailhead the day we start a backpacking trip. That is, unless the trailhead is within 3 hours of home. This way we can start our hike first thing, not after an exhausting cross state drive. I also like to start our hikes early in the morning to ensure that we avoid unnecessary crowds.
With that being said, we arrived in Mammoth on a Saturday around 5pm after a 6 hour drive from SoCal. I mistakenly booked a campsite in June Lake, thinking that we were beginning the hike at the Rush Creek Trailhead. We could not secure reservations at any of the campgrounds in the Mammoth area, so we opted for dispersed camping instead. If you want to learn more about dispersed camping around Mammoth, check out this page.
After rolling into town, we picked up a jug of water to cook dinner and breakfast the next day. We found a pullout off on the Mammoth Scenic Loop to camp for the night.
Day 1: River Trail – Agnew Meadow to Thousand Island Lake (~7.9 miles)
Getting to the Trailhead
We woke up on Sunday in our dispersed camping spot to find that all of our gear was wet. There was a ton of condensation overnight so we toweled off as much as we could before heading to the trailhead.
We parked at Mammoth Mountain Inn and purchased our tickets from the resort. Mammoth Mountain Inn allows overnight/backpackers parking (for free) along the side of the road.
We boarded the 10am shuttle from Mammoth Mountain Inn to Agnew Meadows. We got off the shuttle with a family that was also backpacking to Thousand Island Lake. Though, they started on the High Trail rather than the River Trail. They hiked to Thousand Island Lake a few times before and said that the River Trail was easier than the Rush Creek Trail (June Lake) that I thought we booked our permit for initially. That was a relief to hear.
River Trail
After getting lost in the campground, we finally found the trailhead for the Shadow Creek/River Trail. Most of the River Trail was covered in the trees with a few areas of exposure on the side of the canyon. The weather wasn’t too hot or humid.
We found places to filter water frequently along the trail. A couple also backpacking the River Trail told us the trail is typically drier this time of year (August) but that the recent monsoonal storms brought a lot more water for filtering. So water availability is something to keep in mind on this trail.
The terrain of the River Trail was beautiful and reminded me a bit of the Rae Lakes Loop that we did last year. You can read about that trip here.
Once we got higher up in the canyon, we saw a sweeping view of the landscape including the Mammoth Mountain Ski Area.
Olaine Lake
The first major landmark on the River Trail is Olaine Lake. There’s a nice spot on the Southeast end of the lake to eat lunch. Other than that, the land around Olaine Lake is thick with riparian vegetation.
Waterfalls
The River Trail follows the Middle fork of the San Joaquin River. There are several waterfalls both close to and far from the trail that you can enjoy.
Thousand Island Lake
We reached Thousand Island Lake in the early afternoon. The views were beautiful. We hiked the rocky terrain around the lake to find a campsite. Many backpackers camped directly on the rocks, but we wanted to stay in the trees. Camping in tree coverage gives you extra shelter from the elements, especially the wind.
We set up camp in a nicely nestled forested area on the right side of the lake. Then we went onto one of the rocky outcroppings to spend the rest of the day, enjoying the views. I read my book until the sun started to set. Then we migrated back to our campsite for dinner.
Day 2: Shadow Creek/John Muir Trail – Thousand Island Lake to Agnew Meadow
We were relieved to wake up to a dry tent in the morning on Monday. No condensation this time. I read my book for a bit before venturing out into the brisk morning. We ate a quick breakfast and promptly packed up camp because we saw storm clouds brewing.
The weather forecast predicted a monsoonal storm on Tuesday, but it actually started Monday morning, so we decided to hike out. Leaving Thousand Island Lake, we saw a beautiful double rainbow. It was a nice farewell.
Emerald and Ruby Lakes
After leaving Thousand Island Lake, we came up on Emerald and Ruby Lakes. It was a bit of elevation gain out of the basin that Thousand Island Lake is in. The rain continued as we passed Emerald and Ruby Lakes, so we didn’t spend much time in the area.
Garnet Lake
After hiking out of the basin that Emerald and Ruby Lakes were in, we crested up on the climb to see Garnet Lake. Garnet Lake was similar to Thousand Island Lake but with fewer islands in the lake. The trail around Garnet Lake was longer than Thousand Island Lake so we enjoyed the view for quite a while as we descended to the lake’s outlet.
After reaching the outlet, we started another steep climb to get out of the basin of Garnet Lake.
John Muir Trail & Shadow Creek Trail
Once we reached the highest point of elevation on this day, we descended on the John Muir Trail to reach the Shadow Creek Junction. Because of the elevation gain and loss on this day, I was pleased that we didn’t take this trail up to Thousand Island Lake. The JMT/Shadow Creek Trail approach was longer and more difficult than the River trail.
Once we completed most of the descent, we met Shadow Creek which had a pretty green color to it. Shadow Lake itself did not disappoint.
Shadow Lake
Unlike Olaine Lake, Shadow Lake has several places to sit and enjoy the view of the lake. The water, like the creek flowing into it, was a greenish hue. We enjoyed lunch and the view before embarking on the final leg of our journey.
Shadow Lake to Agnew Meadow
We ran into the same family we met the day before on our way out of the trip. They told us that the High Trail was actually an easier hike than the River Trail with the downside of increased exposure. We’ll keep that in mind when we come back to Thousand Island Lake for another trip.
After returning to Agnew Meadow, we only waited a few minutes before the shuttle came by and picked us up.
Post Backpacking Shenanigans
We packed up our gear and headed into town for food and shopping to cap off our trip. When we are in Mammoth, we usually always go to Mammoth Brewing Company for food (and free parking).
We did not want to drive home after a long backpacking day, so we slept in the car in the same dispersed camping area as our first night in town.
Things that went well
Dispersed Camping
Staying in a dispersed camping spot before and after our trip worked out really well. We stayed close to the trailhead without dealing with campground reservations.
If you haven’t camped in dispersed areas before, it is important to know what amenities and restrictions there are. Dispersed camping areas don’t have access to bathrooms or other amenities that you get at a traditional campground. Some dispersed camping areas also require that you bring your own toilet (of some sort) to your site. Checking the rules in the sites you are interested is definitely important.
Things to Improve
We don’t currently have raincoats for backpacking. Until now, I used a Patagonia Houdini for rain on the trail. Though, that was in Montana where thunderstorms were short and real rain gear wasn’t necessary. I will research a new raincoat for these monsoonal storms and other rain events while backpacking.
All in all, I think things went really well on this trip! I think this is our last backpacking trip of the summer season and it was a great note to end on.
Conclusion
I highly recommend the River Trail to Thousand Island Lake. Please leave any comments and questions below. Check out my other backpacking posts! You can also find me on Medium.