Every year the League of Northwest Whitewater Racers holds a two-day slalom event on the Cedar River at Landsburg, about 15 minutes south of Issaquah. This year the races are March 17 and 18, with the slalom course open for practice all day Saturday, two downriver races on Saturday, and the slalom races on Sunday.
I’m not sure of the cost to race or use the course but I’m pretty sure it’s not much. If you’ve ever thought of trying a slalom course or are just curious I encourage you to stop by – people of all skill levels (i.e., none) and in all kind of boats, including creekboats and playboats, join in. Not to mention that you’ll see some really good slalom kayakers and canoeists (?) as well.