This is an OHV area and the trails can be rutted, eroded, and there can be quite a lot of traffic; not always awesome for hiking.
Early season (even into June) can have closures from water. Check with the Ranger Station before heading out.
Mill Canyon #40 is a scenic and challenging route that ascends from the American River to the Ridge Trail #157.
Start by crossing a bridge and then following the creek along the bottom of Mill Canyon. Within the first mile, you'll hike through a mix of forest types and see some of Northern Utah's red rock formations.
As the route ascends, it breaks away from the creek on its way to an intersection with Mud Springs. Continue straight and rejoin the creek for a easy section.