Anderson Peak NE Ridge

Prelude:
Brief summary of this route... It's scary, but it's there. I wouldn't do it again, but it was worth doing once. Gina and I both got sick around the middle of last week and had to cancel our flight out to Montana where we were originally going to climb Granite and Cowen with friends. Once we were feeling a bit better (not by a lot, but at least a little), we felt comfortable tackling a mountain or two... plus, we didn't want a 5-day weekend that we'd both planned vacation time for to go entirely to waste. I'd been wanting to get out to this area for a while to get eyes on the Truro Traverse, Tabor, etc. We couldn't find much beta for Anderson's NE ridge, outside of a TR that briefly mentioned two folks who split off to tackle the ridge - describing it as Class 3/4 along the ridge proper... Having scrambled it, I disagree. The true "ridge proper" would require stout 5th class climbing up the summit block. That being said, it's a short ridge romp that's high on excitement, but it ended up being a bit more than we bargained for and definitely rustled our jimmies.

Approach/Route:
We drove along the Lincoln Creek Rd (Subaruable until around where Galena Creek meets Lincoln Creek) and then walked the rest of the way to the Anderson/Petroleum Lakes Trail... Hardest part (if you didn't drive to the TH) of the approach is trying to find a place to cross the creek without getting wet. Follow Anderson Lake trail up to the lake, then split off and head up to the obvious saddle SE of the lake. From the saddle, head up the NE-facing talus field (staying along the right side treated us well). Scramble up and over the first tower, which holds some fantastically solid, Class 4 terrain. After the first tower, the rock quality goes to shit. Pick your way down to the saddle between the first and second towers. We didn't like how loose the start of the next tower looked and briefly traversed under the right side of the tower before finding entry onto some class 3 (chossy) ledges that led us back to ridge proper. Scramble up and over the 2nd tower and make your way to the bottom of the headwall on a ridge that's reminiscent of the San Juan Range.

From here, it looked like you could bypass the headwall entirely be descending down and to the left, traversing under the cliffs on the E face, and then gaining the South Ridge, but we weren't ready to give up quite yet. We traversed on a chossy ledge around the right side of the headwall and found a hidden dirt gully. The gully was steep and had a particularly unnerving chock stone near the top that proved to be the crux of the route (at least for us). Immediately after the crux, there's an exposed ledge that takes you around a rock rib. Continue to traverse up and across on Class 3 terrain that leads to a Class 4 dihedral. Climb the Class 4 dihedral and exit onto the ridge via a crack feature (may have required a move of 5.low). Continue up the ridge. There's one final step in the ridge that requires Class 4 scrambling (maybe a move or two of 5.low) before gaining the summit. We continued on to Petroleum afterwards with the intent of maybe linking some other peaks, but the winds finally picked up and since we were still somewhat sick, we headed down rather than be miserable for another few hours.

Route Information:
Mileage: Approximately 10 Miles
Elevation: Approximately 3700'
Class: 5.0
Time to Complete: 6.5 Hours

Exposure: Extreme
Rockfall: Extreme (Be VERY careful in the gully with partners)
Route-Finding: High
Commitment: High

Alternate Route(s)

Thank you @Blazintoes for bringing up the Mountain Project entry that describes another route up the summit block of Anderson Peak! The dihedral described looks a lot more solid than the route described below, though it appears to require some elevation loss to enter the dihedral (assuming it's where I think it is).

https://www.mountainproject.com/route/124578616/north-couloir-east

Additionally, if you want to avoid all 5.low scrambling, it appears entirely possible to circle under the cliffs on the South Side of the peak and then work you're way up gentler slopes to the South Ridge, which appears to be Class 2. From the saddle before the headwall, drop SE, contouring below the cliffs until you're just under about 13,400'. Begin traversing across the slope towards the South Ridge. Please note, this is NOT a route that will allow you to bail into the basin below... the terrain underneath this traverse is littered with loose cliffs. The best way to get off the ridge is to go back from whence you came. Once you reach the summit of Anderson Peak, the fastest way down appears to be a grassy, ENE-facing ramp midway between Petroleum and Anderson Peaks.