Lime Ridge Regional Open Space is owned by the City of Walnut Creek, and provides decent hiking high above the cities of Walnut Creek, Concord and Clayton. The ridge is bounded on the north, east and west by bucolic suburbs and the massif of Mount Diablo to the south. Lime Ridge is a sandstone formation that runs south from Ygnacio Valley Blvd. until merging with larger foothills on the northern flank of Mount Diablo. California buckeye, valley oak and blue oak dominate the drainages while chamise-dominated chaparral clad more open areas. There is also a lot of grazing activity in the area, but you're unlikely to run into cattle on most of this hike. Evidence of past mining activity is evident in the near-distance. Like most of the Bay Area, this is a great place to see raptors.
The hike starts at the parking lot off of the south side of Ygnacio Valley Blvd. at the entrance to the Montecito subdivision. Head west on the Ohlone Trail for a few hundred yards, then turn left onto the Paradise Trail as it heads up the south side of the ridge. The route here is basically an unmaintained dirt road, but turns into a single-track after about 0.5 mile. The trail inexorably, but gently, winds its way up a shallow canyon. Note the large open space and subdivision below to the left that was formerly the site of a quarry.
The forest of California buckeye and blue oak closes in as the canyon narrows and the smooth sandstone trail continues ascending. The trail opens to reveal views of Clayton to the east as you near the highest point of this hike. At the top of the ridge there's a bench beneath some small communication equipment. Most casual hikers head back from here, but it's worth heading straight south on the Lime Ridge Trail for great views of Mount Diablo. You can also dip down to the west on the Manzanita, Lime Ridge or Buckeye Trails to connect with the Ohlone Trail to head back to the trailhead. A better way is to head down Manzanita and then return to the spine of the ridge via either the Lime Ridge or Buckeye Trails. After topping out again return the way you can on the Paradise Trail. - Feb 26 2012 Jim Lyding