Lake Mountain is an attractive Washington Top 100 peak in the Pasayten Wilderness located a couple of miles southeast of Monument Peak and 1.5 miles NNW of Pistol Pass. Though Lake is lower in elevation than Monument, it nonetheless holds its own. It is solitary yet beckoning; rugged yet relenting. In all, it is one of the more memorable peaks in the Lago group of Top 100 peaks. When you see Lake, there is no mistaking what you're looking at. And soon you'll be wanting to stand at its apex. The view of Monument Peak from Lake is top-notch. The name of Lake is a little dubious since there are no real large lakes anywhere near the peak. There is a little 4-acre "lake" called Lake of the Woods in the basin southeast of the peak, but it did not seem worthy enough to name a peak after.
Lake mountain is characterized by a slabby West Face, a near vertical north wall above a tight cirque, a very steep Northeast Face, and a slightly more moderate southeast side. It is speculated there may be some pleasant rock climbing routes on the North and Northeast Faces. There is a long arcing escarpment that runs NNW from Lake to the East Ridge of Monument Peak. This escarpment is quite steep and cliffy on its north side and effectively separates the Lake-Monument Basin from the Monument-Blackcap basin. If coming from the north (say, from Shellrock Pass) to climb Lake, mounting this escarpment will be your greatest difficulty (look for a very steep, un-scarifiable cut/gully just east of Pt. 7688 for an "easy" way up). By far the easiest way up Lake is via the west side or via a long ramp on the southwest side closely west of the southeast crag of Lake (Pk. 8165). A route directly up-ridge from Pistol Pass may not be worthwhile, but I have not been there so can't say for sure. Certainly you will be stopped short of the summit by the aforementioned crag (see photo of Lake taken from Monument Peak).
The Pasayten Wilderness is generally not as rugged as other regions of the Cascades to the west and southwest, but the terrain around Lake Mountain is quite rugged, making the mountain hard to get to. There are three approaches to the peak. The shortest of these would be from 7,100-ft Pistol Pass on the Monument Creek Trail No. 484. It is 11 miles from road to pass then 1.5 miles as the eagle flies to the summit. It is not known what an ascent of the ridge NNW of the pass would be like (I have not been there), but once you get to the south base of the mountain near 8,000 ft you will have to drop either to the west or east to finish the climb due to a crag (Pk 8165) barring direct completion from the south. A probable route and probably the easiest from here, would be to drop down the north side of Pistol Pass, skirt Lake of the Woods, and continue northwesterly toward Lake, finding a gully that bears directly toward the summit area. Another approach, though by no means shortest, would be from 6,960-ft Slate Pass on Harts Pass Road. For this approach, you want to descend from Slate Pass to the Robinson Creek Trail No. 478 as it parallels the Middle Fork Pasayten River. Then once you get to about even with the large horse camp in a large meadow, look for the trail up to Ferguson Lake. In 7 miles, this trail descends to Eureka Creek just south of Monument Peak. From here, you can continue north up Eureka Creek to 7,480-ft Shellrock Pass or find a route eastward around the corner to the Lake-Monument basin. A third approach to the north side of the peak (to Shellrock Pass) would be to continue north on the Robinson Creek Trail to Berk Creek then ascend the Freds Pass trail up, over, and across the head of Eureka Creek.
Permits are not required as far as I know, though signing a trailhead register might be requested. When I was out there for a week in August, I saw less than five people once I got back to the Shellrock Pass vicinity. You'll see more people (and horses and dogs) on the Robinson Creek Trail or Monument Creek Trail, but once you get off-trail, expect to have the region to yourself.
When To Climb
The mountain could probably be climbed in every season except winter. Access depends on conditions for getting to the trailhead. The Monument Creek Trail No. 484 trailhead is at 2,300 ft. The Slate Pass trailhead is ~6,900 ft up. In fact, the road to Slate Peak Lookout is the highest well-traveled road in Washington. Harts Pass Road is also one of the more exposed roads to drive on. Combine that with the many sightseers who use the road and it becomes a concentrating endeavor. The snowier the approach, the longer time you'll need to get in and out. Using the Pistol Pass approach, the mountain could be done in two days (one day if you're traveling super-light and running; it's about 25 miles roundtrip). For the Ferguson Lake approach, assume two days. The mountain will probably require three days if doing the climb from Shellrock Pass. Adding a climb of Monument Peak while in the area would be a worthwhile endeavor, so you could allow yourself the extra day or half-day for this (depending on the direction you're coming from).
There are numerous campsites. Some I know of are:
1. At or near the horse camp where the Ferguson Lake Trail junctions off from the Robinson Creek Trail
2. At the intersection of the Robinson Creek Trail and Berk Creek (this is where the trail up to Freds Lake, Freds Pass, and Lake Doris begins)
3. At Freds Lake
4. At Lake Doris
5. At the eastern head of Eureka Creek immediately south of Mt. Lago
6. At a half-acre sized bench at ~7,500 ft just southwest of Shellrock Pass. This is where I camped for five days. It is a good staging area for climbing all the peaks in the region. There may or may not be a snowpatch there for water. Bring a filter.
7. In the Monument-Blackcap basin NNW of Lake (grassy terraces but a marmot metropolis)
8. In the Lake-Monument basin (prime bear country?)
There is probably good camping near Pistol Pass or Lake of the Woods.
When I was in there in August 2001, I was snowed on lightly for one night at my 7,500-ft camp. Knowing this, plan your clothing appropriately. It can be hot or cold or in between in the Pasayten. Ordinarily, you won't get much rainfall as the wilderness is far east of the Cascade Crest. However, when I was there, it rained for 36 hours straight. I stayed in my tent nearly the whole time.