LIMESTONE CANYON - The 40-million-year-old “Sinks” at Limestone remain one of the most iconic and awe-inspiring destinations in Orange County. You’ll also find oak-filled valleys and year-round springs while hiking the canyon’s 20 miles of trails.

‘LIKE A NATIONAL PARK IN YOUR BACKYARD’

ABOUT THE PRESERVE

Irvine’s Northern Open Space Preserve provides residents an opportunity to visit 20,000 acres of pristine wilderness, just moments from home.

It begins its ascent above the villages of Portola Springs and Orchard Hills and reaches across four canyons on its way to Cleveland National Forest. Along the way, it passes mountains, meadows, lakes, waterfalls and woodlands.

Highlights include Limestone Canyon with its 40-million- year-old sandstone cliffs; Fremont Canyon, bright with poppies each spring; Weir Canyon, home to mule deer and oak woodlands; and Black Star Canyon, where golden eagles soar.

The open space offers a variety of OC Parks trails through habitats of rare species, from the California gnatcatcher to the world’s northernmost stand of Tecate cypress trees. You can access these wonders through guided tours by the Irvine Ranch Conservancy.

When you step into the preserve, you enter the largest urban open space network in America – the only land ever to receive both the California State and United States National Natural Landmark designation. And it is available for all residents to enjoy forever.


LIMESTONE CANYON - The 40-million-year-old “Sinks” at Limestone remain one of the most iconic and awe-inspiring destinations in Orange County. You’ll also find oak-filled valleys and year-round springs while hiking the canyon’s 20 miles of trails.
LOMA RIDGE - A hike to Loma Ridge is one of the best ways to appreciate the scope of the natural wildlands encompassing the Northern Open Space Preserve. The ridgeline, rising above Orchard Hills, offers views from the Pacific coast to the Cleveland National Forest. Photo by Ashish Malik
FREMONT CANYON - Picturesque rock formations, caves and steep canyon walls have earned it the nickname “Yosemite of Orange County.” Rich in biological diversity, this rugged canyon is also home to rare Tecate cypress groves.
WEIR CANYON - Weir Canyon is the northern starting point of the 22-mile Mountains to Sea Trail – the backbone of The Irvine Ranch’s 57,500 acres of open space. Its woodlands and grasslands are scenic, while its trails include a stagecoach route from the 1800s. Photo by Glady Rutherford
BLACK STAR CANYON - Explore 40 million years of geological history in this gateway to Orange County’s backcountry. You’ll be awed by soaring red rock cliffs, sweeping vistas to the Pacific and serene meadows of grassland that hold rare species of plants and animals.