The most complicated so far, and perhaps the longest stretch of river.
The one wrinkle I do not understand the ramifications of is the discovery that the RGB color mode caused the problem with the defined brush not showing up. When I used Indexed Color, then it did work, with the mode choices being threshhold and dissolve. Then when I saved the map as a TIFF file, PSE insisted on making it a "copy", although I could save it as a PSD, too. More to investigate.
The biggest problem is the multi-color stippling: red, pink, brown, black, blue, lying on the river, but often also across the shore. So the first step was to use the pencil as an eraser with the background color. The lettering was removed by magic eraser (which is what required going to Indexed Color), although it leaves little fragments of gray. It was necessary to keep changing pencil sizes to get all the garbage off. Then the river edge had to be repaired, although some black was left, since I didnt want to lose the edge completely before repairing it. There were few contours to fix on the shore, although there was some dotted brown (sand, big rocks?) lost.
I removed the center line, some of the county designations, the reservation and park labels that were on the river, and the label "indefinite" up on the north boundary.
I then restored the river water, single color. It is hard to get an exactly uniform wash of pixels, but at the proper scale, it doesnt seem to matter. I noticed that there are no rapids shown on this quad, unlike some others.
The job left to do is to fix the northern, land boundary. I need to remove the multi-color stippling, which will be new because I dont want to lose the contours underneath. The black line has to go too, which is easy, but again requires repair of the contours.