The reservoirs of the Marin Municipal Water District (MMWD) are the gems of the Marin County open space. And none is better than Bon Tempe Lake, a moderately hike-able lake with quiet forest inlets, open savannas, and great vistas.
This hike follows the edge of Bon Tempe Lake with minimal ups and downs. Although the lake is popular with hikers, runners, and fishermen, because of the many curves in the shore you have a sense of isolation while exploring the shoreline. We saw many fish-eating birds on and near the lake including: cormorants (large black birds seen resting on logs and buoys in the lake), common mergansers (duck with dark red head and long beak with hooked end), and osprey (white fish-eating bird).
From the parking area below Bon Tempe dam (pit toilets only), head up the dirt road towards the dam, which was built in 1949. At the top of the dam, go right to circle the lake counter-clockwise. There are some some great views to enjoy as you look across the lake to Mt. Tamalpais, and down to the fingers of Alpine Lake. At the dam's end, take the signed Bon Tempe Trail into oak and bay woodland (Junction #1 on the map). After a half mile or so, you will see the first of three bridges along the "Shadyside" of Bon Tempe. Up ahead, many of the taller trees are black oak, too tall to clearly see their distinctive leaves, which are 4-6 inches long with deep lobes. Look for fallen leaves on the path.
About a mile and a half into the hike you arrive at the Lagunitas picnic area (Junction #2 on the map). Just past the redwood grove, go left across the bridge into the picnic area. There are bathrooms, picnic tables and drinking water available here. Skirt the Lagunitas parking area and continue left on around the lake. The large set of valves is used to send water from the lake to a water treatment plant (gravity fed). Junction #3 on the map can be tricky. Just stay to the left along the lake. A dirt road (seldom used) goes inland.
You are entering the peninsula area of the lake. The habitat is different, more open, and there is evidence of the habitat restoration MMWD is doing here. They have left the large Douglas Firs that stand majestically on Pine Point peninsula overlooking the lake. The area is also rich with bird life. Osprey and great blue heron fish in these waters. Cormorants, gulls and wintering ducks also spend time here. Pileated woodpeckers and red-shouldered hawks nest in the trees.
The trail meets up with the paved Sky Oaks Road. Go left along the road until you round a corner past a bathroom on the right and you reach a small parking area on the left (Junction #4 on the map). Leave the paved road to follow the trail along the "Sunnyside" of the lake. The open grassland is quite dry and hot in the late summer. We saw lots of small fence blue bellies lizards scuttling off the trail ahead of us. When you reach the end of the dam go right, back down to the parking area.