Hwy-89 from Logan to Garden City (Logan Canyon/Logan River) has a few no-hookup campgrounds through the canyon, and most will be walking distance to the river and dams. Once you get North of Right Fork (Camp Lomia) you can boondock almost anywhere.
IIRC there are 2 campgrounds between Logan and Right Fork. The one I can remember is really close to the Wind Caves.
There is one campground at the end of the pavement of Right Fork. There are a couple spots to boondock on the Right Fork road between 89 and Camp Lomia, but are usually taken on the weekends. At the end of the pavement on Right Fork, if you veer right and go through the gate (now heading due south), there are some places to pull off for the evening, but this takes you farther from the river. There is no need to go very far before you are out in the middle of nowhere. I don't know how far you want to get off the pavement... Did a lot of tent/truck camping up there in college. I don't remember what was to the left.
Temple Fork Road is (was not) a bad road to go up a short piece and spend a night or two. After a little bit it opens up again for a nice place to park next to a small stream. Camping next to Logan River isn't going to happen here.
There is an open field near the USU Forestry Field Station that I've seen many trailers at during hunting season (and holiday weekends), that place you near the river. Nice open spot.
There is a camp ground just before Tony Grove Lake (paved road to lake) that is on a hill side. There is also a camp ground on that 1500' spur right off of hwy89 that has paved spaces, but most are not level (like run out of tongue jack on your trailer not level). I THINK there was fresh water available at this one but I'm not making any guarantees.
I almost forgot. There is a road just before 3rd Dam; Google Earth marks the turn off at 41*45'07, 111*43'35. Boondock and fish right there 50' from your rig. In college we usually went there and fished and camped.
My order of preference.
1. Just down river of 3rd Dam. Free, right at river, flat road.
2. Boondock on Right Fork Road - near river, free, no room for a second rig to crowd you.
3. Campground (either one if there was two) between Logan and Right Fork - you're near the river for fishing, nice in cool in the canyon, plenty of shade trees
4. Camp Lomia at the end of Right Fork - still near river for fishing
5. USU Forestry field - free and near river
6. Tony Grove CGs - gonna pay a few bucks, but good fishing at Tony Grove Lake. Is a steep but paved road all the way to the Lake.
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