Mostly want to pass along advice on the parking... easy access to this trail and to the Upper Lewis River Falls can be had from Lewis River Horse Camp parking area ... there are more spaces (16 vs 8) at this location compared to others and it seems to have way more last minute availability ... and there is a .3 mile connector trail that goes basically right down to both trailheads (upper falls is just across road 90). After Sept 15 it won't be an issue because parking restrictions will be off.
My son and I backpacked up Lewis River last week but also hiked about a half mile up Quartz Creek to check it out too ... this trail appears a little more challenging and I am planning to return to dayhike up to the 5B cuttoff and back tomorrow.
All the trails up there that we hiked were in great shape and bugs were very light ... have fun!

We hiked from the Middle Falls trailhead on the Lewis River trail, then onto the Quartz Creek trail, to Straight Creek.  

The sections of trail that we did are in good shape, with a few downed trees that were easy to get over.  The bridge at Platinum Creek looks like it's been down for a while, there is a small plank currently in place, then a short scramble up along the remains of the old bridge.  

Straight Creek was our turn around point as there was no obvious way to cross, and we were not about to ford this  wide, swift, and slippery-looking creek.

We hiked from the Quartz Creek trailhead on 90. I know the lower part of Quartz creek well, hadn't seen much upstream. Plenty of water for the dogs in the initial few miles, crossing Straight, then Snagtooth, then Quartz creeks. The only question on the route was at this point crossing Quartz creek and finding the trail on the other side - it's a bit up the creek from the near side, but didn't take long to find. Soon after crossing Quartz creek we took the right (east) fork, a connector trail between the Quartz creek (#5) and the main Quartz Creek ridge (#2) trails. To make a shorter loop we skipped finishing the hike on the #2 and instead headed down the hill on forest road 9075, then took NF90 as planned back to the trailhead. It was a 15.6m route, very big trees, and we enjoyed the complete solitude.

The below was written after hiking the trail on July 2nd.  I went back today, August 17th, and I'm happy to say, had much more success.  Trail crews have been at work, the logs I had to climb over last month are cleared.  The muddy areas are dried, and easier to navigate (still steep enough to need caution!).  All the creeks are low enough to ford.

I went as far as Snagtooth Creek, crossed the creek, and took a short break in the campsite there, then headed back.  I did not see the trail on that side, but I also didn't look too hard for it.

The only other people I saw on the trail were 3 people who were packing up their camp on the outgoing side of Straight Creek.  Otherwise, it was mine, although the parking was packed with vehicles when I returned, people going to Lewis River.

(Most of the descriptions for this hike are missing from the site, but I found it elsewhere, and wanted to try it.  The drive to the trailhead is long, but a lovely drive, and easy to do.
The trail itself was rather difficult to navigate.  It's up and down, when it went down towards a creek, the trail was very muddy and slick  I had a trekking pole, but didn't feel that safe going down, and ended up choosing to slide down.  According to the description I found, there are 3 creek crossings.  I gave up at the 2nd crossing, which is Straight Creek.  The first one is where a bridge once was, and that was easy enough, but there was a lot of water in Straight Creek, and I didn't feel comfortable that I could cross it.  Especially as I wasn't sure what other obstacles might lie ahead.  And I had a dog with me, who I believe is shorter than the creek was deep.

So, we turned back.  It was very lovely for the short distance we did.  I filled in the short hike by heading down the Lewis River trail a ways to look at waterfalls.  I'll probably try to go back later, when water levels are lower.)

Trail is nice and pleasant the first 1.5 miles. It is a road that abruptly turns into a trail and reminded me of the closed Dirty Harry’s trail. Overgrowth comes and goes 2 miles after this. I kept going to around 4.3 miles or so, which felt like wandering aimlessly through extreme overgrowth at times. Somehow there is a trail through all of that. At this point, there was a bit of an opening and the trail kept going but I did not so I can’t say how much further/worth it after that. Very quiet area. I was alone the entire time but it’s easy to see why. Grade is similar to nearby Granite Lakes. I would recommend downloading a map as there’s no signal, a few side trails, and extreme overgrowth in areas.