San Luis Reservoir is for boating and fishing, not for wandering through the hills. The place is HOT in the summer, no trees, but if the mountains are calling and you must go, thankfully you don't need to go far. Presenting Pacheco State Park.
Many state parks preserve an incredible feature of nature (huge sequoias, a piece of shore at Lake Tahoe, beachfront property in danger of being developed). This is one of the newer parks, and it preserves a cattle ranch that was owned by the family that gave Pacheco Pass its name. 140 years after the ranch started, the owners deeded it to the state to be a park. With the development that happened in California over the last 100 years, this means that this land is untouched from before statehood, with the exception of pickup truck roads, water reservoirs, and barb wire fences.
It is scenic indeed, with landscape typical of the park near where I live, Mt. Diablo. Gnarly oaks sit in wide meadows on rolling hills. Endless picnic areas. Look south, and you see a rugged Ridge that's not part of the park. Natural ponds. Nice views if the weather is good (I went on a cloudy day). The hills are easy to follow, so you can stroll across the meadow (leave no trace) because there are not many trails for such an expansive park. From one end of the park to the other is roughly 3 miles.
I've seen nicer landscape, though, and in open space districts with no entrance fee. Hence the 3 stars. Still, if you like to wander in a lesser-known park with few people, Pacheco fits right. It's possible that the fee you paid at San Luis will work at Pacheco.
Big note: When you leave, if you're turning left to go toward Hollister, it may be easier to turn right instead, drive a few miles, and then make a U turn at the entrance to the cottonwood preserve. Rain had started to fall when I left in mid-March, and Highway 152 is a terrible place to be the victim of a fatal car accident. Even with the scamdemic, I'm not THAT eager to see the Lord before He says it's time.
Bigger note: NO WATER. This place is as hot as the San Luis Reservoir in the summer, so come with more than what you need. Don't count on someone to pass by to offer help.
Pacheco State Park is worth a visit of several hours. I was there for 2-1/2 and it wasn't enough. Who needs Monterey, anyway? read more