I've hiked at the Cosumnes River Preserve several times and noted that they encourage kayaks. The Cosumnes is one of the few undamed rivers left and the Preserve is an effort to restore the habitat to it's original state. You'll see a LOT of birds of every type as well as otters, beaver, and turtles. The website www.cosumnes.org is the best place to get detailed information. Start the trip at the Middle Slough and head left towards the river. On the left, there are some reed beds that are home to red winged blackbirds. You'll also see otter play slides on both sides of the slough. When you get to the river head left again towards the train overcrossing. Just before the overcrossing, there's a small slough on the right with a beaver lodge. Proceed up the river. When the river splits into a Y, you'll see some benches on the right. This is one of 2 permitted take out and rest places (The Point). Go straight up the river, or veer left for a really long slough. On one side is the preserve, and on the other a levee that protects some farmland. It's all forest and then there's a small clearing and the second legal take out and rest. There weren't any benches. If you turn back here you'll have about a 3 hour, very easy outing with some great bird sitings..egrets, hawks, kingfishers, and more.
The river was extremely calm and flat with almost no noticeable current. However, the flow can be impacted by tide levels (the river connects to the ocean through the Delta) and runoff from High Sierra storms or snow melt. During the summer there could also be very low water conditions.
The visitor center has maps, trip instructions, and restrooms. The river has only rest stops (can't take out and leave) and no other facilities. Pack it in, pack it out. The Visitor Center does a great job with a display and information for kids so this is a good family outing.
Take I5 south from Sacramento and exit at Twin Bridges road. Head east. Just before the train tracks (about a mile) make a right at a stop sign at Franklin road. About a mile down on your left is the Cosumnes River Preserve Visitor center. The road deadends just past it. There are instructions for loading and unloading.
River/Creek (Up to Class II)