The Preserves website has lots of information on activities and other things to do including a great paddling guide with map.
The following is taken from the Consumnes River website:
"It is the only remaining unregulated river on the western slope of the Sierra Nevada. In its lower reaches, it flows through one of the biologically richest regions in California's Central Valley, before merging with the Mokelumne River to flow into the Sacramento-San Joaquin Delta and eventually the Pacific Ocean. The Cosumnes River Preserve was created to safeguard much of this unique landscape.
The free-flowing nature of the river allows frequent and regular winter and spring over bank flooding that fosters the growth of native vegetation and the wildlife dependent on those habitats. More than 250 bird species, more than 40 fish species, and some 230 plant species have been identified on the Preserve.
The lower Cosumnes River offers excellent flat water canoeing and kayaking opportunities during most of the year. Paddlers can enjoy a scenic glide through the river's sloughs and main channel, crusing along riparian forest, oak woodland and through wetlands teeming with wildlife. "
There are restrooms and free parking available and there is no launch fee. It's a good idea to bring a cart to carry your boat to the launch site. The visitor center has carts available to borrow if needed.