Los Vaqueros Watershed: Tarantula Run half marathon route

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In the San Francisco Bay Area, one of October’s characteristics is that it is considered to be tarantula season, when male tarantulas are on the prowl for mating opportunities. During a recent long hike on the Ohlone Wilderness Trail in the Ohlone Regional Wilderness I encountered two tarantulas. And just a few days later, during a hilly training walk at Stanford’s The Dish, I saw a third tarantula. As a result of these encounters I decided to traverse the route of a recent race hosted locally, called the Tarantula Run. It was also an opportunity to experience the route of a half marathon trail run, without any pressure or expectations about my finishing time.

Los Vaqueros Watershed, owned and operated by the Contra Costa Water District, was the site of the Tarantula Run. When I arrived at the entry kiosk I mentioned that I was planning to try the race route, and the ranger had copies of the route maps that he offered me, though I had brought my own annotated copy downloaded from the event web site. He also mentioned that there would be fantastic views. I knew that there would be about 2200 feet of climbing – a lot for a street half marathon, but perhaps not for a trail route – and that the event cut-off time was 4½ hours on-course, corresponding to an average pace of 20-minute miles – faster than I usually hike, especially if I take pictures, which I did plan to do. So this was an experiment in several aspects.

The route was a balloon or semi-loop configuration, with the first 2.2 miles repeated at the end and a main loop of nearly 9 miles. The orange dot on the GPS track shows the start at the Kellogg Creek Picnic Area. As it happened I had a little trouble with route-finding that would not have happened during the event. This added about 0.9 mile to my distance.

GPS track

GPS track

It turned out that the first route-finding challenge was finding my way to the Kellogg Creek Trail. Just east of the picnic area there was a gated trail entrance, but at the end of a short stretch the signage indicated that the Kellogg Creek Trail turned left, when it actually turned right. I initially followed the signage and had a detour over to the Administration building before I got back on the intended route. This pretty view is across the Kellogg Creek Picnic Area toward the hilly area where I would be going.

photo of view from near the Kellogg Creek Picnic Area

View from near the Kellogg Creek Picnic Area

Alongside the trail, both near the beginning and in several other places, there were quite a few of these late-blooming yellow flowers with leaves reminiscent of rosemary and distinctive 3-lobed petals, or more likely ray flowers.

photo of yellow flower found in several places along the route

Yellow flower found in several places along the route

Because of a couple of detours near the beginning of the route, at 3.1 miles – instead of at 2.2 miles – I crossed the park road and reached the junction with Crest Trail, where the main climb begins. This was a sustained climb of nearly 1000 feet in just 1.5 mile, with an average grade of 12%.

Elevation profile

Elevation profile

I don’t typically try to power-walk up such steep sustained climbs, so I was actually glad to have several scenic reasons to pause for photos. There were nearly continuous views of Los Vaqueros Reservoir, changing and, I thought, getting better as I gained elevation. This picture was taken from an elevation of about 840 feet. The dam is at the left, and it is clear looking at the shoreline that the water level is lower than usual.

photo of View of Los Vaqueros Reservoir

View of Los Vaqueros Reservoir

There were also nice views generally to the northeast, with Kellogg Creek at the bottom of the canyon and – I think – Frank’s Tract, a lake that is part of the San Joaquin River delta, in the right background.

photo of view to the northeast from Crest Trail

View to the northeast from Crest Trail

Looking closer to the trail, I found numerous spider burrows with webs covering the openings. I don’t know if this was a tarantula burrow, or the precise significance of the web covering (e.g. catching food, or protection from predators).

photo of spider burrow along Crest Trail

Spider burrow along Crest Trail

About 1.3 miles up Crest Trail the route makes a right turn on Vista Grande Trail and continues to climb. Shortly after the turn two benches are located near the trail’s crest. Surely the views from the benches were part of the fantastic views the ranger had referred to. I really had the sense that I was king – or queen – of the hill! I think Brentwood is in the background of this picture, and the trail for a later part of my loop is on the ridge in the center of the view. Note the bare branches of buckeye trees in the immediate foreground.

photo of view from a bench along Vista Grande Trail

View from a bench along Vista Grande Trail

Looking ahead along the trail instead of off to the right, there were intermittent views of Mt Diablo about 7 miles away, peeking over the nearby hills.

photo of Mt Diablo

Mt Diablo

Particularly along the high part of the trail there were western bluebirds alternately catching insects and perching on a nearby fence. Farther along Vista Grande Trail I noticed a distinctive-looking rock. There don’t seem to be names for any local features on my maps, but I thought it looked a bit like a turtle.

photo of turtle-shaped rock along Vista Grande Trail

Turtle-shaped rock along Vista Grande Trail

After about 1.2 miles on Vista Grande Trail, with a few small hills, the route turns right at Eagle Ridge Trail and makes one more 100-foot climb before starting the major descent. There were several plants with light purple blossoms: a bit of a surprise for so late in the season.

photo of light purple flowers along Eagle Ridge Trail

Light purple flowers along Eagle Ridge Trail

Near the beginning of the descent there was a nice view of some hills with contrasting flora: bare, grassy hillsides facing open-forested hillsides.

photo of contrasting facing hillsides

Contrasting facing hillsides

The initial part of the descent down Eagle Ridge Trail was pretty steep for runners, with a grade of over 12.5%. The footing wasn’t bad for walking, but I generally do slow down on unpaved hills with such steep slopes. The final 1/3 mile of Eagle Ridge Trail has an even steeper grade of 15%! Just past this steep section the route turns left at Grassland Trail, where there are a couple of small rollers as the trail continues to descend. Along Grassland Trail I happened to notice a single stark white animal bone in the grass. I estimate that it was almost 1 foot long.

photo of animal bone near Grassland Trail

Animal bone near Grassland Trail

The half marathon route continues about ¾ mile on Grassland Trail, then turns right on Kit Fox Trail for about ½ mile (and a 100-foot hill) before a right turn on Salamander Trail at the top of a second 100-foot climb. Salamander Trail continues for another mile, with a third 100-foot hill, before reaching Walnut Trail, which follows the park road. As I was climbing the third hill, on Salamander Trail, I noticed some movement on another hillside ahead of me. It turned out to be a coyote, presumably on the prowl for a meal. In the picture the coyote seems to be looking at me, but I was too far away for that to be the case, unless – like me – it noticed the movement.

photo of coyote


After I reached Walnut Trail I turned right to follow next to the park road. Forgetting to consult the route map, I missed a turn onto Greasewood Trail. At the next trail junction I realized that I’d made the error and simply went up the side trail to its next junction, then back to Walnut, to roughly compensate for distance. As I went up the side trail I could see what I believe to be Greasewood Trail snaking up the low ridgeline.

photo of trail on a low ridgeline in Los Vaqueros Watershed

Trail on a low ridgeline in Los Vaqueros Watershed

After about 2 miles on and near Walnut Trail I closed the loop at the Crest Trail junction. From here I simply followed my outbound path – omitting detours – back to the start at the Kellogg Creek Picnic Area.   Along Kellogg Creek Trail I noticed a few more blooming wildflowers, such as this pretty pink-tinged white flower growing close to the ground. Unless it is a morning glory well past its prime, I’m not sure what it is.

photo of pink-tinged white flower along Kellogg Creek Trail

Pink-tinged white flower along Kellogg Creek Trail

I also noticed a buckeye butterfly that I seemed to be chasing down the crushed gravel trail: it would land on the trail, pause, and then fly off down the trail as I approached. Open-field birds (e.g. sparrows, meadowlarks) on the fences next to trails seem to exhibit this same behavior. It is as though they do not quite realize that if they flew past me – at a safe distance, of course – they would be past the danger they perceived.

photo of buckeye butterfly

Buckeye butterfly

When I arrived back at the race staging area I had covered 14.3 miles in about 4 hours 50 minutes. Even with all of my stops for pictures, I had maintained essentially the pace needed to complete the intended route barely within the time limit. In that sense it was a successful experiment in a trail-based half marathon. This kind of trail run is quite a bit more challenging terrain than the other half marathons I have walked, which have mostly been on regular paved roads. By the way, I didn’t see a single tarantula.

This entry was posted in Contra Costa County, East Bay, walking for fitness and tagged , , , . Bookmark the permalink.

3 Responses to Los Vaqueros Watershed: Tarantula Run half marathon route

  1. readersguide says:

    I don’t know what that yellow flower is, but I saw it yesterday in Sunol regional wilderness — right next door. Good pace, too. That’s fast!

    • trailhiker says:

      I also saw the same yellow flower recently in the Ohlone Regional Wilderness. There are very few flowers in bloom this late in the season, but I haven’t yet found a resource that identifies late bloomers. If you come across anything, please let me know!

  2. Pingback: Los Vaqueros Watershed: Valley View and Homestead Trails | trailhiker

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