I will post a more personal trip report soon. For those who may be planning a trip and about to leave on a North lake - South Lake loop here is my recent experience strictly about trail conditions.
1. July 27-28 Tyee Lakes Trail to Tyee Lakes over Table Mountain to George Lake and out to Sabrina: Trails in generally good condition with only two unremoved deadfalls. Trail from Table Mountain to George lake sketchy at times as its old switchbacks crossed sandy soils. 1/2 mile long (but not wide) snow bank on top of Table Mountain hides the trail; best to cross to opposite side when the trail runs into it and follow the bank until the trail comes out the other side.
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2. July 28-29 Piute Trail from North Lake to JMT. Entire trail seemed in reasonable good shape with no deadfalls I remember. Piute Pass has a snow bank a few hundred feet long on the east side but horsepackers have excavated a wide level path through it with only one 20 foot steepish section.
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On the west there stream crossings headed into Humphries Basin that have made the trail a creek for a couple of hundred feet, but can easily be picked around or splashed through. The stream crossing coming out of Desolation can be managed without wading by heading upstream a couple of hundred feet and picking your way across the multiple branches. At Hutchinson Meadows put on your waders when you hit the first stream and don't take them off till you have finished the whole bunch--8 if you count the little ones. They all come within a couple of hundred yeards. There are one or two more streams to wade as you approach the famous West Pinnacles Creek ford.
West Pinnacles Creek is scary because the water is so turbulent that you cannot see the bottom and judge the depth. However,
at the time I waded it there were areas that were no more than knee deep--but you cannot see that, you have to measure it with your poles. Wade in the wrong spot and you will wind up in a hole. You want to use the two feet on the downstream side of the crossing area--not downstream of the trail but on the downstream side. This won't be obvious by looking, but will by probing. Whatever you do, don't wade straight into the middle--the 3/4 of the crossing area in the middle and on the upstream side have been scooped out into a hole. Feel your way to be sure you stay in shallow water.
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3. July 30 JMT from Piute intersection to Evolution Valley. Mostly well maintained as you would expect for one of the most popular trails in the world. A rainstorm created some additional wading just before the trail heads up to Evolution Valley.
Evolution Creek crossing had notes from the ranger indicating that the regular crossing was no more than two feet deep and safe now. I watched several strong young hikers cross there before deciding to go to the meadow. There had been recent rainstorms and the regular crossing did seem to be knee deep much of the way but somewhat deeper than that on the far side.
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The meadow crossing was very manageable. Thigh high on me (I'm only 5'7") but placid, clear, easy to see the bottom. It does help to walk diagonally downstream rather than crossing completely perpendicular to the current, allowing the current to help you take your steps.
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Ranger Station in EV is manned and provides weather reports and trail conditions.
4. July 31-Aug 1. Evolution Valley over Muir Pass to Le Conte canyon. The inlet to Evolution lake is easily wadable, although cold and wide--mostly calf deep. There is intermittant snow beginning as you round Evolution Lake and Sapphire Lakes, then long almost uninterrupted snow walking from Sapphire to Wanda. I stayed west and crossed the Wanda outlet right at Wanda, others crossed lower down and trudged up the snow on the east side. I don't know that it made any difference. Wanda lake is still mostly frozen--except for a small patch near the outlet where some neighbors were catching fish. Almost all the shoreline has a little water showing, though it froze over again thinly at night. The trail along the east shore of Wanda is still mostly covered, but there is about 30% ground exposure.
From Wanda to Muir Pass is all snow. The trail cuts to the south of a tarn adjacent to Lake McDermond, but most people seem to cut to the north of the tarn, step across the stones dividing the tarn and the lake, and then begin the trudge to the SW of Lake McDermond nearly straight to the pass. Following the previous trudgings was a godsend--the suncups were often a couple of feet deep and letting others tramp them down. I stayed the previous night on a desolate tentpad at Wanda and went early in the am. Using the microspikes it was almost like walking on concrete.
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From the pass down to Helen Lake was much steeper than the Wanda side, but also straightforward.
The trickiest part for me was deciding which route to take from the outlet of Helen downstream. Numerous hikers continue not to cross the outlet at the lake but cut high across the snow south of the stream. I thought that looked a little too exposed for my abilities. It was actually easy to cross the outlet stream immediately at the lake--just stepping stones, and about half or more of the actual trail is now exposed on the way down. There were a couple of points where snowbanks/stream/cliffwalls pressed together and I needed to do a little scrambling, but it seemed much safer than the high snow path to the south of the outlet stream. The rangers warn of the use of snowbridges in the area.
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Le Conte canyon has a lot of water in it and a few stream crossings--none particularly challenging, although I watched as a trail companion fell on a simple one. There are no "easy" crossings.
5. Aug 1-2 Bishop Pass trail from JMT to South lake. The trail was in decent shape up until the infamous "Dusy Switchback" crossing. Just before that crossing there had been an avalanche leaving a dozen or so deadfall all over the trail. Earlier I met a nice young trail worker heading up the Bishop Pass trail (who would not tell me where they were working--I think for security they are instructed not to) but I never saw any work being done on the trail during my hike. It would take a couple of people half a day to saw these mostly smallish deadfall and they still had not done so by August. In the meantime the trail area was becoming a maze of detours as hikers climbed through them tearing up the area. What a mess.
For those who don't know about the Dusy switch crossing, it is the first major crossing of Dusy Creek you come to when coming uphill, and the first crossing of Dusy creek you come to after the earlier footbridge crossing when coming downhill. I watched as two men crossed on stones and two small wet logs 20' upstream from the trail. I could not bring myself to do it--both the logs and the stones looked slick, the logs only covered about 1/2 of the creek, and jumping and fine balance were required. Wading did not look promising either, I was horrified when I stuck my poles in and they almost disappeared. Finally I remembered my West Pinnacles Creek experience and wondered if there could be a pattern. YES! Again, on the downstream quarter of the crossing area the water was no more than knee deep, but you cannot tell that by looking due to the froth. It turned out to be a straightforward wade.
The trail through lower and upper Dusy Basin was fine, began to hit a few patches of snow when getting well over 11,000 feet. The snow was inconsequential except for some minor switchback diversions getting near the top. The pass itself was clear of snow.
From Bishop Pass down to Bishop lake there were a couple of hundred feet of snow walking on relatively level snow near the top. On the cliffy switchbacks there were only a few minor patches of snow that blocked nothing important and caused no safety issues that I saw. The stream crossing at the inlet to Bishop lake required a safe wade. The trail all the way to Long Lake and to South Lake was in reasonable shape. Between Saddlerock lake and Long Lake some people (I presume horsepackers) have excavated the trail 10' deep through the few snowbanks remaining--I am guessing so they can get their livestock over it.