I'll be fishing the Green River in Dutch John UT for four days in early July. I have all the recommended terrestrials but I'm looking for suggestions for streamers/dry/wet flies.

Back in the middle ages when they did jousting the riders carried those long blunt-tipped spears for knocking the other guy off the horse. You might need one of those on the Green in July. To keep the other drift boats a good social distance away.

It's a beautiful river filled with trout. There might be some Pale Morning Duns still hatching that late.
It's a tailwater river. Scuds, flashback nymphs, small mayflies. Streamers of any kind.

When there is no visible hatch and the fish are not actively rising most people fish wet flies on the bank. A lot of the local guides there tend to fish small nymphs deep. Brightly colored scuds of any kind on a looooooooooooooooooong leader. With weight. Cast upstream. Straighten up the line so you can feel the strikes. Funnel your concentration into the fly line. And down the leader. So your mind is fixed on the fly. Even if your wife is yelling at you you can't hear it. Because every muscle in your brain is fixed on the end of your leader.

Repeat as needed. Where ever faster water drops off into a deeper/slower pool is good. If they aren't rising near the edges that is.

The guides concentrate on the top A section float. The B section (next ten miles down stream) gets much less traffic. There are fewer fish down there but some are big. That water is all streamers and big grass hopper fishihg.

I've never fished the C section. I'd like to. I've done white water floats starting maybe 90 miles downstream from the dam. Where it's all catfish and brown water. And big big white water in the canyon.

I caught my biggest on a crayfish fly. In August when the hatches are finished fishing deep, in the middle, is the only way. The skilled fishermen come earlier. In August the customers are all beginners. At the slowest time. That makes it tough.

In August the guides put small balloons in the line followed by a long leader a pumpkin ball weight and two scuds. You can't cast that rig. They troll it through were fast meets deep and slow.

It does tell you something about wear the fish are in late August. Late June early July on the other hand, is prime time.

A few years ago someone caught a 20 pounder. Right at the dam.

Finally. The Missouri in Montana gets insanely crowded in July too.

I usually only fish there spring and fall.

But this year the crowds are way way down. The Green might be relatively empty too. This year. Might be totally cool.

We were able to choose from many un-reserved campsites right there in the park near Dutch John. That speaks for how busy they are in the parks. I'll be taking a variety of Online recommendations of terrestrials and streamers but I'll buy the wet flies, drys and Nymphs locally once I get there. I'll be bank fishing. My son might manage a raft rental.

Hike or walk down to Red Creek Rapid. It won't be much of a rapid in July. It's worth the trip at least once. The rest of it is relatively smooth. At Red Creek there is pocket water and the fishing is less fussy.

Thanks for the tip.