RE:Exploring the Green
Try floating it with the Puma from the Geyser down to Soos Creek... I'll bet you see two dozen summer runs holding or moving around. For shore fishing you'd be better off fishing up around Palmer State Park -or- even the Headworks Dam.
Is anything holding in Horseshoe Pool? Probably dozens of big slabs. Climb up the ridge on the right bank and take a look in the pool mid day, try not to fall off when you see the slabs finning there. Best way to score is to get there 1 hour before the ranger shuts the gate and fish it over the rock garden (head of the bend) with a purple butt spey or similar fly. Very best is to camp in the park and take the three hours before they open the gate at 8am to tease up a mondo trout.
Like all rivers, it takes time to learn it.... Good luck!
The first stretch along the gravel road at the Headworks Dam holds beaucoup summer fish, and getting there early usually means fish on. Walk up and swing the fly as you work down. Keep going downstream past the pump house and work a muddler in the rapids.