Dogs are allowed off-leash in the Shell Ridge Open Space, but are not allowed on the western part of the trail where it enters the Mount Diablo State Park.
Take a short climb up an exposed sandstone slab followed that will bring you around the corner to an amazing view of pine canyon and the rock formations on the left. As you pass the second stream crossing look for climbers on your left up on Pagoda Rock.
Follow the relatively level Stage Road stage road as it runs along the middle of the canyon and the stream switches back and forth across it multiple times. The trail should be in pretty good condition and doesn't get too sticky even when it's wet - but there can be big rocks under the water and the streams can get up to a foot deep and flow pretty fast when it's been raining. If they aren't flowing quickly, the line across the streams is pretty well defined.
The end of this segment is the east bay regional park boundary where there are a couple of picnic tables under the shade of trees. The gate marks the park boundary with Mt Diablo state park on the other side. Make sure that you close the gate properly - the state park is mixed use land and there are often cows grazing the other side of the fence.