It turns out Sylvan lake was not dead, as I thought it was. It turns out I was just fishing in the wrong place. It was chock full of Green Sunfish, Pumpkinseeds, and Bluegill, but mostly greens.
We must have 20-30 Greens apiece in the creek. I also managed to snag a pumpkinseed on the belly... What was up with that?
Bluegills were present as well.
The biggest success of the day was seeing some mystery fish swimming around. For a fish to be a mystery in freshwater NJ is pretty hard to do. They were long, skinny, and 10-15 inches long. Their dorsal fin placement, there light brown color, their forked tail, as well as rounded head, made me think sucker, but their fins were black-tipped and they showed some interest in the spinners that I through at them, one of them even nipping it.
It was strange, and may warrant a couple trips in the future to try to figure it out.