Places We Protect

Santa Rosa Plateau


TNC’s Santa Rosa Plateau Ecological Reserve protects nearly 10,000 acres of California’s southwest Riverside County.
Santa Rosa Plateau TNC’s Santa Rosa Plateau Ecological Reserve protects nearly 10,000 acres of California’s southwest Riverside County. © Kevin Horan

TNC long knew the value of the Santa Rosa Plateau and fought to preserve it.



It could have been an endless sea of red tile roofs. Instead, an oasis took shape in the midst of southern California’s urban sprawl—the Santa Rosa Plateau Ecological Reserve—offering hikers and other nature enthusiasts the opportunity to enjoy some of California’s rarest landscapes.

Coaxed out of the surrounding malls and housing developments, the plateau protects nearly 10,000 acres of southwest Riverside County, including unique Engelmann oak woodlands, some of southern California’s rarest native grasslands and the region’s last remaining vernal pools. The Santa Rosa Plateau Ecological Reserve and other protected lands in the area—known collectively as the Santa Rosa Plateau—comprise an unusually intense concentration of extraordinary species rarely encountered anywhere.

Saving Space

In late 1983, Riverside County’s population was edging close to 750,000, and development was booming, with enormous plans in the works. Concerned with protecting the many unusual species of the plateau, TNC worked to purchase 3,100 acres from a housing development company.

In hindsight, the purchase of 3,100 acres sounds so simple. Yet it belies the scientific research that precedes any purchase we make to determine if the property in question will produce the greatest conservation outcomes. It fails to convey the enormous effort that goes into the fundraising, negotiating and closing of an acquisition like this. TNC long knew the value of the plateau and fought to preserve it.

Since 1983, we have worked in partnership with the local community and a host of local, state and federal agencies to secure today’s total of nearly 10,000 acres of the Santa Rosa Plateau. Through this series of strategic additional acquisitions, we have focused on developing a wildlife corridor that links the plateau to the Cleveland National Forest, providing room to roam for wildlife, like mountain lions, that need space to survive.

Continued Achievements

Santa Rosa Plateau represents one of the California program’s great achievements.

In July 2011 TNC transferred its remaining properties and two of its conservation easements in the area to the California Department of Fish and Wildlife (DFW).

Complementing our transfer were two important acquisitions. DFG acquired the Santa Rosa Springs property, the only previously unprotected private inholding of the reserve through which Cole Creek flows. And the Western Riverside County Regional Conservation Authority acquired another important priority property in the corridor. TNC assisted both of these acquisitions.

A Suburban Oasis

Twenty million people live within a 100-mile radius of the Reserve. It is indeed a beloved and needed oasis, with more than 60,000 visitors annually, including 7,000–8,000 schoolchildren. There is an active volunteer program that always welcomes new members. The fact that the Santa Rosa Plateau receives so many visitors is a testimony to our need to get out on the land, and this vast and amazing landscape is there to fulfill that need.

The Reserve is always seeking volunteers. For more information please call 951-677-6951 or email




Chaparral-covered hills, Engelmann oaks, vernal pools, two-striped garter snakes, rare fairy shrimp

Explore our work in this region

What You’ll See

While the plateau’s chaparral-covered hills are iconically Californian, a rare treat awaits the visitor who makes it to the mesa tops—thousands of acres of native grasslands and Engelmann oak woodland, one of the rarest oak species in the state. Many an expert has voiced that the plateau supports the best example of native grasslands in California. The Reserve is also home to the Santa Rosa basalt brodiaea.

Vernal pools, large shallow ponds that fill with each winter’s rains, were once common in southern California in springtime. But years of development have taken their toll, and the Reserve is home to some of the last remaining vernal pools in the state. Today, a boardwalk allows visitors to “walk on a vernal pool” without disturbing it and to see the riot of life that erupts when the pool fills. From the rare and threatened fairy shrimp, found nowhere else on Earth, to tadpoles and two-striped garter snakes, the vernal pools are brimming with small-scale action.

Visit the Santa Rosa Plateau.