Located north of Arlington, WA. (I-5, exit 215). Nice mix of logging roads and single track. Trails were developed and are heavily used by Equestrians. It's a pretty good push to the top but the views are worth it. Lots of roads and trails to explore.
Go north on I-5 to exit 215 (300th Street) and get off. Turn right and go about a mile to English Grade Road and turn left. Go about 2-3 miles to 316th and turn right and up the hill. At the top of the hill, turn left, through the Gla**chool gate and park at the lot provided about a quarter of a mile up the road on the left. If full, you may park just inside the gate to the left on the grassy area there. Hint: shadier on those hot days if you want to come back to a cool car. Trails eminate from all points. Will take some exploring to put your favorite loops together
http://www.singletracks.com/item.php?c=1&i=1014