Marin hike: A lovely lakeside loop at Bon Tempe

For pure enjoyment, it’s hard to beat the lakeside loop around Bon Tempe Lake.

The lake has two long sides, called “Shady” and “Sunny,” for obvious reasons. Although there are several entry points, we will begin our clockwise circle of the lake at my preference, the Shadyside trailhead. We will then cross Bon Tempe’s dam and traverse Sunny’s welcoming atmosphere, before taking the final leg back. At any time in any season, the hike around Bon Tempe Lake is a holiday of treats.

• Summary of hike: The Bon Tempe Lake loop hike is an easy 4 miles with some gentle up and down and good footing. There are port-a-potties at the Lake Lagunitas parking lot. No dogs allowed.

• Getting there: Take Bolinas Road out of Fairfax to Sky Oaks. Turn left on Sky Oaks, and drive slowly upward to the top and by a ranger’s admission booth. Some 50 yards farther, pull off to the right and purchase an automobile day pass for $8 from the ticket machine. Drive to Lake Lagunitas on the main paved road to its end.

As you are about to enter the lake parking lot, there is a large sign: “Lake Lagunitas Picnic Area.” On the right, a few feet later, there is a short road to the right with some adjacent picnic tables. Our trailhead is down that road, left at the green gate and just over the bridge to the signed Shadyside trailhead on the right. You may park in the Lake Lagunitas parking lot, along the short road to our trailhead or elsewhere nearby.

• The hike: From the Shadyside trailhead, we are greeted by the woods, fragrance and birdcall. After walking through trees near the lake for a short distance, we arrive at a pleasant open verge bordering the lake before entering the woods again. Over each gentle rise and around each turn, the light, shadows and plant life shift — almost as if we were entering different forest rooms. We will cross three bridges on our way to the dam.

In the woods, the trees determine the understory plants and trail habitat. Shady’s trees are largely Douglas fir, redwoods, tanoaks and bay (laurel) with a few maples and black oaks scattered about. The trees on Shady make their presence known, as you must look through them and their changing shafts of sunlight and shadow to view the lake.

In the middle of our Shady walk, there is a spot on the trail where you see straight ahead a tall dead tree with taller Douglas firs surrounding it and a large osprey nest on its top. I was told the osprey is incubating its eggs, visible only occasionally when it shifts its position and shows its head. I never saw it.

I did see a great blue heron perched on a fallen tree with some mergansers sitting farther down the trunk. The heron soon chased them off. A short distance later, I observed a merganser mother swimming in the lake with several small furry baby ducklings paddling after it. A bit farther and closer to the bank, some Pacific pond turtles were sunning contentedly on a log.

Arriving at the dam, we walk across it. Below on our left, we see what I call “Alpine Lake’s tail.” The lake will lose it over the dry months, and then, during the winter rains, it grows its tail back like a lizard.

At the dam’s far end, we descend the crushed rock road, take a short bridge over the lake’s dry spillway, and just past a narrow trail rising steeply on our right, we turn right on the larger trail that is level for maybe 5 feet before it begins to climb. Its climb is somewhat steep but short, and soon we crest and begin our hike on Sunny.

Initially, we encounter a few madrone trees that are probably remnants of the former pasture lands that were flooded after construction of the dam and Bon Tempe Lake in 1948. Interior live oaks are the dominant tree on Sunny with a few bay trees and water-loving alders lakeside. As we traverse Sunny, we are treated to various unobstructed views across the lake to Mount Tamalpais.

The spring wildflowers of Shady have already disappeared or are in their last stages, but on Sunny, there are still many wildflowers scattered among the high grasses.

At Sunny’s end, we pass the trailhead for Sunny and turn right on the dirt path adjoining the road. We continue for a while along the lake before descending a few steps to turn left at the signed Pine Point Spur Trail. We continue until the sign pointing to Lake Lagunitas via the Alex Forman Trail and follow it. Just before reaching the road, we curve right past a trail sign with many symbols but indicating nothing else. We continue uphill with no lake view, then across a large open area, past an Alex Forman Trail sign, and across a road. From there, we take a jog to the left to the path toward parked cars and the Lake Lagunitas parking lot.

I hope you enjoyed this terrific hike. I will be on vacation for my next scheduled column but I will see you next on June 24.

A longtime avid hiker and Marin resident, Jim Holden is the author of two nonfiction books: “It Happened in Marin” and “Adventurous Lives, Daring Acts.” He can be reached at MarinhikingJim@gmail.com.