Mud Mountain Dam Park (seven miles southeast of Enumclaw [1] off Hwy. 410, 360/825-3211) contains one of the nation’s highest earth-and-rock flood-control dams. The park is a fun place to take the young kids to toddle. There is a wading pool, playground, picnic areas, and scenic overlooks.
Older kids with more stamina will appreciate a scramble over at least part of the 10 miles of hiking trails that unravel on the grounds.
Links:
[1] http://www.moon.com/destinations/washington/south-cascades/cle-elum-area/enumclaw