Oursan Trail

Length: 1 – 10 miles (go as far as you want and turn around)
Time:  2 hours for a 5 mile hike
Difficulty: Easy to Moderate.
Elevation Gain:  Fairly flat trail with a few little hills
Dogs:  Yes, but must be kept on a leash at all times.  This is one of the few EBMUD trails that allows dogs.
Best Season: Spring!
EBMUD Permit:  Required
Calories: Around 900 calories for a two hour hike
Highlights:  The Oursan Trail skirts the northern shores of Briones Reservoir, through open fields and scattered oak trees and is one of the most serene hikes in the East Bay.  It is especially stunning in the spring when the meadows are green with wildflowers and the direct sun is welcome.
Directions to Bear Creek Trailhead (from Lafayette):  From Lafayette take Happy Valley Road up over the hill to Bear Creek Road.  Take a right and then a quick left into the Bear Creek Staging Area.   This staging area is on the opposite side of the road from the entrance to Briones Regional Park.
Trailhead:  Once you have parked look for the gate and trailhead on the right/north side of the parking lot.  The Bear Creek Trail starts on the other side.

This is the best hike in Lamorinda for walking adjacent to a reservoir besides the Lafayette Reservoir, which is far more crowded.  You’ll see a few people on this trail on the weekend, but it is very lightly used.  The name “Oursan” is as lightly used as the trail.  It means “small bear” in French, but I’m not sure when or why it  was chosen.

Briones Dam was built in 1964 to supply growing central Contra Costa County with water (that’s us!).  The Reservoir is very deep and the largest of EBMUD’s reservoirs with a total capacity of 19.7 billion gallons of water.  EBMUD manages the reservoir and the watershed land that surrounds it.  Local runoff into all five reservoirs satisfies about 5% of the East Bay’s water needs.  The rest comes from the Pardee Reservoir in the Sierra.

To start the hike, go through the gate, sign in at the registration kiosk with your permit number, etc. and then proceed on the fire road.  The trail climbs steeply from the trailhead over a small hill, then opens up to a view of the reservoir.

First view of the reservoir.

You will pass a giant oak on your left with large clumps of mistletoe.  We commonly think of mistletoe sprigs as something you hang at Christmas time to kiss under.   Mistletoe is actually a very large family of parasitic plants that attach to and penetrate the branches of a tree or shrub, through which they absorb water and nutrients.  For a long time, Mistletoe was limited to the foothills around the Central Valley but today it is commonly found throughout the Bay Area and seen in many mature Oak trees in the East Bay.

Besides the big oak tree you may be flanked by hundreds of California Poppies.   They flower from February through September, but spring is when they put on the best show.  This is the flower pictured on welcome signs when you enter California!  It was selected as the state flower in 1890, as its golden blooms were deemed a fitting symbol for the Golden State.  April 6^th is California Poppy Day.  A few fun facts about the poppy:

• The petals close at night or in cold, windy weather and open again the following morning.
• Poppy leaves were used medicinally by Native Americans, and the pollen was used cosmetically.
• It is drought-tolerant, self-seeding, and easy to grow in gardens.

Besides poppies, you are likely to see buttercups (small yellow flowers), lupine, and blue-eyed grass.

After passing by the lake’s edge, the trail will take an up-and-down course around two fingers of the lake, often under a canopy of oak trees.   You may notice a nest box for wood ducks.  In many areas, wood ducks have difficulty finding suitable natural nesting sites. These boxes provide a man-made alternative, where hens can nest in relative safety from predators.

Red-winged Blackbird

Ducks are just one type of bird you might see.  In the open areas you may see red-tailed hawks, red-shouldered hawks, or turkey vultures flying high above.  In wooded areas you may see varied thrush, western scrub-jays, and band-tailed pigeons.  In the water look for ducks and grebes foraging near the shoreline. On a recent hike (April 2020), we kept seeing red-winged blackbirds along the edge of the lake on and around cattail (see picture).

After about a mile, the trail emerges from the trees and runs out in the open, along the water, for another mile or so.    You will have many excellent views of the shimmering blue water and may think it would be great for swimming or boating, but it is not open for recreational use.  There is one exception:  it is used by the Mills College, UC Berkeley and Saint Mary’s College rowing teams, which I’ve seen on one occasion.

Keep track of your time and turn around when you have hiked half as long or half as far as you want to go.  I typically hike about an hour and then turn around.    At 5.4 miles you reach the Hampton Trail, which connects to the Hampton Staging Area.  The Oursan Trail actually continues for a lengthy 10.4 miles, ending at San Pablo Dam Road.  If you’re really up for a multi-hour adventure you can connect to the Bear Creek Trail and complete a 14 mile loop around the entire reservoir.

Selfie picture at turnaround point with friends Rick & Alicia!

Tags: Bear Creek Staging Area, Briones, dogs, oak trees, poppies, views