Discovery Peak is accepted as the highest point in Alameda County and is located on the crest of Valpe Ridge. For many years, nearby Rose Peak was thought to be the highest in the land, until the famous highpointer Dinesh Desai "discovered" a higher point a couple miles to the east of Rose Peak in 1991, hence the name Discovery Peak. To make matters more complicated, there are several points within a few square miles of Discovery Peak that rise to 3840 feet, suggesting that Discovery Peak may not be the highest. See this thread for more info on the subject. Best to tag Discovery and Point 3480 to the southeast if you are a purest. Discovery Peak is very remote and obscure. Located deep within the Ohlone Regional Wilderness, getting to the peak requires a minimum 7 mile hike in, and an elevation gain of over 4000 feet. The surroundings are typical that of the Diablo Range. The ridges are covered in oak and grey pine, as well as grass. Views from the top stretch across the immediate surroundings, Mount Hamilton and to the south, Mt. Diablo to the north, the SF Bay to the west, and the Sierra Nevada acros the Central Valley to the east. Discovery Peak is located on private property, yet located only about 1 mile off the Ohlone Wilderness Trail, so the trespassing zone is not very far at all. Discovery Peak would be considered S2 on the Sneak Peak Climbing scale.
The approach to Discovery Peak begins at Del Valle Regional Park. This is where the trailhead is. From Livermore, head south on Livermore Road, and this will bend east and turn into Tesla Road. Turn right at the Mines Road traffic light. This is located just as you're coming out of town. Take Mines Road for a 5 miles and bear right onto Del Valle Road. You will see signs pointing to the park. Descend into the Del Valle and soon you'll come to the park entrance. Pay the entrance fee ($ 6.00) and continue on the main road. You will also need to pick up a permit to hike the Ohlone Wilderness Trail ($2.00). Cross the bridge and turn left. Proceed about 1/4 mile and you'll see the Vallecitos Trail head up to the right. This is located just across the road from the campground. Park in the campground and pick up the trail.
Follow the Vallecitos Trail .8 miles up the hill. It will end at the Ohlone Wilderness Trail. Note the little posted sign at this junction. This is marker #40. You will see the little Ohlone Trail symbol on the sign as well. Turn left and begin to ascend the trail. Keep left at the next junction. Continue about .9 miles after that and the trail will begin to descend into Williams Gulch. Cross the creek at the bottom and ascend back out of the canyon. After 1.5 miles, you will gain the ridge, at about 3100 feet. Turn left at the junction at the top of the ridge and continue on a series of Up-Downs for 1.25 miles to Schafer Flat. The road bends west here. Follow it and ascend a bit more. Once you hit marker #32, .8 miles later, leave the Ohlone Trail and follow the fire road that heads south. Shortly there is a Park Boundary Sign, marking the beginning of private property. Follow this road to Rose Flat. There is an old corral and some sheds at the Flat. At this point, Discovery Peak is clearly visible with its radio towers jutting out of the trees. From Rose Flat, head directly east, for .25 miles and about 200 vertical feet. You have now made it to the highest point in Alameda County. Re-trace your steps back.
Even thought Discovery Peak is located on private property, it is very remote ranchland, and the chances of any landowners seeing you is slim.
Parking does cost 6 dollars at Del Valle. You need a permit to hike on the Ohlone Wilderness Trail as well, and these can be purchased for 2 dollars at the park entrance. Bicycles are not allowed on the trail. The park service does close the park if there is a high fire danger, so keep that in mind.
You are allowed to camp at designated campsites. Call 510-636-1684 for reservations.
Discovery Peak is best visited in fall, winter, or spring. Temperatures are quite mild in fall and spring. Spring would bring green grass and wildflowers. Winter might bring snow. Fall would bring nice colors on the trees. With temperatures in the triple digits in the summer, the hike would be utter misery. Not only that, but the park service closes the trails when there is a high fire danger.