Hmm missed this one. For stretches of the Dupe it depends on if you want to fish east branch, west branch, or main stem, as they all fish differently. The east branch is slower, muddier, and generally deeper than the west branch, which has a lot of shallow riffles and the bottom is typically very rocky. The main stem has a bottom consisting largely of sand, smaller rocks, and shells. All hold targetable smallmouth populations. For the east branch, I've historically fished from Lisle on down to the confluence of the east and west branches, although I have tried as far north as Butterfield Rd. The farthest north on the west branch I've gone is I-88, and that only once. I rarely go north of Naperville and fish down to the confluence. The main stem I really just started to venture into maybe two years ago, and haven't gone farther south than around 135th. These stretches offer a ton of water to cover and fish are located throughout.