"The Tassajara Creek Trail is located in the southeast portion of Mount Diablo State Park (MDSP), between Highland Ridge Road and Riggs Canyon Road. The original 1.25 mile section of the trail, which largely runs parallel to the Tassajara Creek, was build by the East Bay Trail Dogs in 2003. At that time the property (known as the “Silva property”) was owned by Save Mount Diablo, but was later transferred to MDSP. This original section of the Tassajara Creek Trail has also been referred to as the “Trillium Trail” due to the abundance of Trillium plants growing alongside the trail.
In 2009, at the request of MDSP, the East Bay Trail Dogs built a 0.75 mile extension of the Tassajara Creek Trail to bypass most of the (now-abandoned) Bob’s Pond Fire Road. A picnic table, also built by the East Bay Trail Dogs, is located where the original and new sections of the trail meet, overlooking Bob’s Pond."
We fought a battle with ticks, especially on the lightly travelled Jeremiah Creek Trail. Due to the remoteness, I would suggest hiking this route with others rather than going solo. There is quite a bit of diversity here. You'll see some nice canopies on the Tassajara Creek Trail, and some exposed and open fire road trails on Morgan Creek Road, Highland Ridge Road, and Morgan Ridge Road. Don't forget to pack a lunch and sit at the picnic table overlooking Bob's Pond.