The Des Plaines River Bike Trail runs along or near the river for about 50 miles. While biking the trail the weeks before the annual May race, I often see workers from the forest preserve clearing out fallen trees and branches in preparation for the race. Otherwise the marathon would be dangerous and require a lot of maneuvering, difficult to do against current and when the river is crowded with other watercraft.
The major obstacle to paddlers is the series of dams. Some can be paddled over during higher water levels, as this one could if the water were higher, because V-shaped boat notches are cut out of the concrete dam (near the right shore on this dam south of Route 60). In lower water levels, the spillway (expanse of slanted concrete) and some posts below the spillway could harm boat or boater. And portaging is difficult due to overgrowth on the banks and very steep sides on most banks. Negotiating dams when paddling upriver would be even more difficult, so I always paddle between dams which gives round trips of 10 miles or more. The Lake County Forest Preserve District is gradually removing many of these dams and weirs, most of which had been installed generations ago by farmers who had owned the property abutting the river.