This week's walk is on one of those few Peninsula trails located within a stone's throw of hundreds of homes. And thousands of nearby residents can walk to one of several trailheads leading into the canyon.

We suggest starting this loop hike from the trailhead at the end of Carlmont Drive, where there is a parking lot for about 12 cars and a locked vehicle gate. A trail sign identifies this as a Belmont City Park, open from sunrise to sunset. Dogs are permitted on leash. Pass through a narrow gate and hike to the end of the canyon floor. This is a broad meadow area with all the signs of a planned housing development, from an asphalt road to a fire hydrant. At the end of the asphalt, turn right and you will see two unmarked trails, both of which climb to the ridgeline above. Take the trail farthest into the canyon, along a drainage channel, and begin climbing. The channel was once reinforced with concrete, which is now broken in various places. The trail climbs through small oak and bay trees and crosses the channel on narrow wood plank bridges. At one point, the trail along the channel is washed out, and a diversion trail is in place farther up the hillside.

The trail crosses the channel on a wider three-plank bridge and begins to climb to the east over another plank bridge. Soon views of homes along Hastings Drive open up. As the trail gains elevation, the trees thin out and are replaced by shrubs and grassland. A narrow, unmarked trail leads downhill to the right, but the main trail continues up to the ridgeline. The trail is steep and rutted in places, but quite passable.

After a steep stretch, the trail levels out, passes an oak tree on the right, and presents long views of Redwood Shores, Foster City, the San Mateo Bridge, and the East Bay.

At the next junction, an unmarked trail to the right brings you back down to the trailhead. Continue to the left through a grassy field to the ridge top, where two signs indicate a junction. To the left is a trail that circles to the south and east. To complete the Water Dog loop, turn right and continue along the fire road trail, which parallels the rear fence line of homes. Views are at their best at this point from Ralston Avenue below to San Francisco in the distance. Soon the trail leads to another trailhead at the end of Somerset Lane off Sherborne Drive in Belmont. The level walk continues to another trailhead at a wooden gate in the 2600 block of Somerset Drive. Near the gate is a trail sign directing hikers to move off the ridgeline into a beautiful ravine filled with oak, bay, and shrubs. Soon the trail climbs out of the ravine and back to the ridgeline. From there, the trail meanders along the hillside, past large plastic drain pipes being installed, and on to the junction with the Water Dog Lake Trail. There is another trailhead off Hallmark Drive, and street parking is available.

It's all downhill for the next mile and one-half, as the trail/service road passes Diablo Canyon and alongside Water Dog Lake. This trail was once a road leading over the hill to Laguna de Raimundo, now deep below the surface of Crystal Springs Lake. Water Dog Lake, created by a dam built in the 1800s, was originally a reservoir providing water to Ralston Mansion in Belmont. Fishing is permitted, but swimming and boating are prohibited.

Continue to the end of the trail at Lyall Way; turn right on Lake Road, and walk for a block to Carlmont Drive. Turn right again, and walk by a series of apartments, the Peninsula Jewish Community Center, and through the Hidden Valley home development to the trailhead parking lot.