(Cascade Locks, OR) -- Starting May 22nd, if you plan to visit Multnomah Falls you'll need to buy a timed permit. The parking lot gets overloaded, and the permit system helps keep spaces available. You can buy a permit for two dollars at recreation dot gov. You can buy a permit up to two weeks in advance of your visit. Each permit covers a one-hour time slot and then you can stay as long as you want.