Trip report
Oct 4, 2020 — Flat Top Mountain is the high point of the Oquirrh Mountains, and an ultra-prominent peak in Utah. Despite its proximity to Salt Lake City, it took me this long to hike it because the route requires getting permission from the landowner to access the summit and I hate dealing with getting permission to go hiking. I knew it was a peak I had to do at some point, and Weston Ault (the landowner) was very nice and gave me permission quickly. His email is aultw [at] msn [dot] com. Assuming you get permission, the drive to the trailhead is fine for any vehicle. 4WD vehicles can make it all the way up to here: 40.35249, -112.21685, but I wasn't willing to risk it. The road was in overall decent shape except for a few rough spots.
I hiked along the road from the trailhead up to the 4WD parking area, where I expected to find a bushwhack, but in fact a well-defined trail switchbacked up the slopes. I got a few minor scratches, but it's a great little trail. I added a couple of cairns where the switchbacks weren't as clear, so just pay attention and if you're not on a really well-defined trail, you're off-route. Once above the switchbacks, the trail continued along the slopes, mostly avoiding the hilly ridgeline by staying on the north side and instead forming big switchbacks to avoid excessive steepness. At one point, the trail enters a forest and passes "No Trespassing" signs, which I assume is the spot where the permission to access the route was required. The trail emerges from the woods on the west ridge of Lewiston Peak, and continues more steeply with a couple of small Class 2 sections. The trail actually skirts Lewiston Peak on its northwest slope, but a social trail continues away from the main trail and up to this minor summit. I read somewhere that Lewiston Peak required a bushwhack, but I encountered no brush. The social trail continued steeply and brush-free down on Lewiston Peak's north side and back to the main trail.
I continued along the ridge up to Flat Top Mountain, only a short Class 2 talus field serving as an obstacle. The views were nice from Flat Top Mountain's summit, despite the wildfire smoke.