Vernal Pool – Hidden Valley – Los Santos Loop Trail

The Trail and the Plants

The Santa Rosa Plateau is an Ecological Preserve located just outside of San Diego County above its northern border. The preserve is set in Temecula Valley, which is the backdrop for the 1884 novel ‘Ramona’ by Helen Hunt Jackson. This fictional novel was based on hard facts surrounding the brutal treatment of the Luiseno Indians that had made the valley their home for millennia.

This great inland valley held a large lake (Lake Elsinore) in its northern section and featured extensive Oak woodlands, meandering streams, vernal pools and chaparral-covered hillsides. There are two Oak species here, the Coast Live Oak and the blue-green Engelmann Oak. There is an impressive 400-year-old specimen shading the Moreno and Machado Adobes that are located in the preserve. Equally impressive is one of the largest Vernal Pools in the state, the nearly 25-acre pool on the Mesa de Colorado.

We will explore this remarkable area via the 4.2-mile Vernal Pool – Hidden Valley – Los Santos Loop trail. The Vernal Pool trailhead is at the southern end of the preserve just off Via Volcano which branches off of Tenaja Road. From the parking area the trail heads east along the Mesa de Colorado. Off to the right (south) are two large vernal pools that are not accessible from the trail. Waterfowl and bird song accent the open grassy meadows surrounding the wide path. In early spring Blue Dicks seem to pop up everywhere. Tucked in with the mostly invasive grasses are the pink blossoms of Southern Checkerbloom and tall stems of Soap Plant. On the left clumps of Vasey’s Prickly Pear dot the field. We quickly come to a trail junction, the Los Santos Trail, which will be our return track.

Continuing straight ahead I often hear the sound of Meadowlarks, perched high on trees, singing their variable song as they watch over the meadows below. Just on the left is a young Engelmann Oak with it’s unique blue green leaves while California Poppies brighten the meadow grass on both sides of the trail. Another trail junction comes quickly; this is the Trans Preserve Trail that cuts across the whole preserve. Ahead there is a large Laurel Sumac with its large folded leaves on the left and just beyond the trail begins a moderate descent and views of the large Vernal Pool come into view.

This very large Vernal Pool is some 25 acres in size (some reports say it is 39 acres when completely full). It rests over an impervious basalt base, which allows it to hold water during the rainy season. This seasonal flooding creates the conditions for a unique palette of plants, those that can take long inundation and also long dry periods in summer. It will be the outer edges of the pool that first come into bloom. One of the first will be the bright yellow blossom of Goldfields.

From the main trail take the short side trail on the right to a raised walkway the goes out over the edge of the pool, allowing you to get up close and personal with this rare environment. In the moist meadow near the pool is a rare native bulb, the purple flowered Thread-leaved Brodiaea. As the pool shrinks the drier outside areas come into bloom in a series of colorful blooms. A white ring of Hooked Popcorn Flower, a low growing form, will brighten the water’s edge.

At the pool, when the waters recede, are some really interesting and some very showy plants. The very colorful blue lavender Spotted Downingia is the star performer. There are magical drifts of this here. The beautiful leaf of Clover Fern graces the ground near the boardwalk while the silver flowered San Diego Button Celery juts up higher.

As you come off the boardwalk there will be more Thread-leaved Brodiaea and another early blooming yellow annual, the small but bright Stickyseed.

As you come off the boardwalk there will be more Thread-leaved Brodiaea and another early blooming yellow annual, the small but bright Stickyseed.  This short side trail loops back to the main trail, turn right and head out across a truly lovely meadow area. Look out ahead down the line of the trail and you find San Gorgonio and Mt. Baldy framed on the horizon. It is matched on the right with a view of San Jacinto. Early spring will often find these peaks capped with snow. Near the middle of the meadow is an outcropping of rock with a bench set to stop and enjoy the vistas. All around are Grape Soda Lupine, California Poppy, more Goldfields and Stickyseed, Field Popcorn Flower, both California Everlasting and Two-Color Everlasting, the amazing Ground Pink and many Shooting Stars. This is a very pretty area.

At the end of this meadow the trail veers right and drops through a grove of small Oaks. Watch out for the Poison Oak that clings near the base of these trees. There also the white flowers of the vining Wild Cucumber climb up and around all the plants. Gracing the lightly shaded areas the light lavender blooms of Caterpillar Phacelia greet us in spring. Just past the Oaks an open grassy area is highlighted with bright yellow Buttercups. On the left at the edge of the grass are a few large Toyons with their clusters of bright red berries in late winter and early spring. The largest must be 20 x 25’; it takes some time to get this big.

Ahead is a chaparral slope and the trail through it is called Fairy Lane for the white Mariposa Lilies or Fairy Lanterns that can be found here. In here we find the shrubs Black Sage, Chamise, Scrub Oak, Sugar Bush, Manzanita and White Flowering Currant. The fragrance you get while walking through here is pure and natural. Some of the smaller subshrubs and perennials to look for are the White Fairy Lanterns, the wavy leafed Soap Plant, Deerweed and the small yellow flowers of Sticky Cinquefoil.

On leaving this chaparral area there is a group of Live Oaks on the left and a view bench in the grass on the right. There are a few Chocolate Lilies near the bench and more in the meadows along the trail as it descends into the valley below. At the next trail junction is an access road that leads to a pair of ancient Adobes, remnants of the original 1850’s Rancho (just 0.1 mi. distant). Turning right at the junction will take you to the old ranch site where a 400-year-old Live Oak casts shade over the old Adobes. We will continue our hike up the ranch road on the left.

The ranch road glides across beautiful grassy meadows surrounded by Oak groves, a reminder of what old California used to look like. As the road curves right there is a junction on the left, which leads to Hidden Valley, take this path. Quickly we reach the Transpreseve Trail junction, which cuts a north-south course across the park. On the right is Poppy Hill, where in a good spring California’s state flower holds court. Continue on straight to a gentle rise and a view of Hidden Valley with its windmill and old corral.

This is a beautiful, sheltered valley with a small creek running through it. Coming out of the valley, on the right hillside, are many silvery leafed Grape Soda Lupine and in spring clouds of Branching Phacelia. Past this valley is another large meadow area. In a short ½ mile the junction with the Hidden Valley cut off trail comes in on the left, take this track down into a smaller valley with several large Sycamores lining a creek on the right. Near the end of this valley, on the left, is the junction with the Los Santos Trail, the last leg of our hike.

Turning left on the Los Santos Trail we climb back up to the mesa. As the trail snakes along an Oak studded ridge look back at the valley views we just came from. In spring, up on the mesa there are stands of Peony on the right and Milkmaids in a small drainage on the left. The trail winds across the mesa and then drops sharply into a small valley only to climb again back to the mesa and join the Vernal Pool Trail that we came in on, back from the Old California vistas.