Sandy River Delta
If you're looking for a day adventure with your dog, head just outside of Portland, about 30-minutes, to Sandy River Delta. The Delta isn't really a park or designated hiking area, but offers 1400-acres of undisturbed land to explore and discover. With the exception of the Confluence Trail, between the parking lot and bird watching area, the entire area is off-leash and dogs can wander freely. If you have the time, hike down to the banks of either the Columbia or Sandy River so your dog can swim -- it is a couple of miles from the parking lot and most trails lead there. Remember to bring water for you and your dog -- there is no running water at the park.