Interesting that you would ask that, Dylan, since I was thinking about trying that summer before last. I hiked part of the High Sierra Trail route with a Pants Pass detour, and wanted to try fishing Wallace Lake, since I'd heard there could be some good fishing there. Someone also told me he was sure Arctic Lake would have good sized fish, so I wanted to fish that one, too. I spent a lot of time staring at the contours of that ridge crossing trying to convince myself it was possible. It is a big clue, though, that RJ Secor does not mention a route across that pass. (He also says the north side of Whitney is climbable, which I was hoping to try, but then I realized the only reports I'd seen were of climbs made in snow -- Crampons and ice axe make really steep slopes climable, that otherwise are not.)
Well, somewhere along the way, I realized I might be delayed on my exit time, so I took the JMT almost to Guitar Lake, and then headed up to Arctic Lake. Looking up at the ridge between Wales and Arctic lakes, I was really glad I'd decided to skip it. It was too-steep-to climb granite; descending would be impossible without rappelling. As for fish in Arctic Lake: zero, zilch, none! The lake appeared void of anything but green moss covering all the rocks under murky water. No sign of fish at all. I tried a few casts, but of course, nothing.
I then continued on up to the Whitney Russell pass (skipping the north slope of Whitney), making it down to Iceberg lake at 4:30. There I filled up zip lock bags with 3 quarts of water, and went up the Mountaineers Route to stay overnight in the summit hut. I need to finish my
HST trip report with this info.
If you're wanting to visit Wallace Lake, I'd just plan on heading up the creek from the JMT, and returning via the same route. You could spend at least a day up there -- Rogue Photonic posted a video sometime back catching voracious (but not huge) trout there.
If you went on up to Mt Russell, it is tough route -- finding the right descent might be tricky if you hadn't climbed it. I believe it is more technical than the Whitney MR. Doing all that with a full JMT backpack would be difficult.
Heres a Gmap4 map of the area:
Arctic Lake