The river is flowing at 1640 cfs and has actually come up in the last couple of hours. This tells me they have lowered the dam in McHenry and are draining off some of the Chain in preparation for winter.
With the temps the way they are though, the fishing could be nothing short of excellent if you are in the right spot at the right time.
1600 cfs can knock you on your ass if you're not paying attention, so be careful out there.
My choices would be Indian Trail Road, west side north of the road, east side south of the road.
Montgomery, starting at Route 30 and going down to the railroad tracks. West side best side till you get within about 200 yards of the tracks, then be east, well, maybe. Okay, zigzag back and forth.
A little further down in Montgomery, start a couple of hundred yards north of the bike path over the river at Violet Patch Park, fish the west side all the way down to the old broken dam. Get out there on the east side and walk back to your car on the bike path.
Orchard Road, half mile up stream to 1 and 1/2 miles down stream. Maybe further either direction. The north side is the more productive side, but some zizagging wouldn't hurt.
Then there's creeks. Probably not much fish up in them anymore. But it sure as hell is going to be pretty.