Shell Ridge is the City of Walnut Creek's largest open space unit, with trails for biking, hiking and riding through oak woodlands and grassland savannah on the lower flanks of Mount Diablo. Shell Ridge gets its name from the marine fossils left behind when the ocean waters that once covered the area receded.
This is a great hike but you need to do it when it is completely dry. The trail crosses what is usually a creek but is completely flooded and requires getting wet to pass if it's been raining. We had to turn back and go through Buckeye Ravine. About 75% of the trail was mud even after 4 days of no rain. The views are great. There are really only two areas of steep incline but besides those, it's an easy hike.
Rajesh M. on Shell Ridge - Borgess Ranch Loop
Avoid in rainy days.
Viral D. on Shell Ridge - Borgess Ranch Loop
Good trail. Decent hike. Scenic. Avoid if it rained recently or if you are going to do it anyway, make sure you wear good trekking shoes. It was muddy when we visited as it rained on three previous day.