A glimpse of the new O.C. park

They walked through land with a storied history, following in the footsteps of Native Americans and explorer Gaspar de Portola, Spanish and Mexican land barons, rancher James Irvine and billionaire developer Donald Bren.

They carried backpacks and cameras, pushed strollers and bombed down hills on mountain bikes. And after the gates to Limestone Canyon closed for the day Saturday, a few hundred people had gotten a glimpse of the future of Orange County’s park system.

“There is so much beauty back there you wouldn’t believe it,” said Dave Swartout, 52, after finishing his bike ride. “It’s a hidden gem of Orange County that most people don’t know about.”

Not for long. What had for generations been private became public in June when Bren and his Irvine Co. transferred ownership of 20,000 acres of relatively untouched lands to Orange County for use as open space.

Saturday marked the first time since the transfer that the public was given unfettered access to a portion of a remarkable swath of steep canyons, grasslands and forests few have ever seen outside of guided tours.

“These lands were protected for their conservation values,” said Mark Denny, director of Orange County’s parks department. “But part of that protection was to ensure the public’s access for recreation and education. We want the public to know that this is all yours now.”

But don’t lace up your boots and head into the backcountry on your own just yet.

Park officials and the nonprofit Irvine Ranch Conservancy, which has managed the property and will continue to do so under contract with the county, plan to increase public access in gradual stages to ensure that the area’s rich and fragile ecology will not be trampled.

“A model would be Laguna Coast Wilderness Park,” Denny said. “It took 7 years to transition it from an Irvine Co. property. For the first few years, all activity was docent-led. Then it was open to the public on weekends. Then, seven days a week.”

The recent acquisition is almost five times the size of Griffith Park. The gift from the Irvine Co. stretches from the 91 Freeway south to the city of Irvine and is bordered by the Cleveland National Forest. Much of its rugged canyons lie in a rare and biologically diverse Mediterranean climate zone.

For years, outdoor lovers had only photos of the sweeping vistas and dramatic geology behind the fences and the Irvine Co.’s ubiquitous red-and-white no trespassing signs. The nonprofit conservancy was established in 2005, in part, to organize limited docent-led excursions.

As a first step to increasing public access, parks officials and the conservancy plan to offer more unstructured “wilderness access days” like the one Saturday.

“Our primary objective is to protect the land. But in order to do that, you need to connect the community to it in such a way you build a constituency of supporters,” said Michael O’Connell, the conservancy’s executive director. “I want some kids in Orange County to make a connection with the land the way I did as a kid.”

One such kid was 4-year-old Isaac Carpenter, who walked hand in hand with his father, Mike, through a meadow dotted with magnificent oak trees.

“He pointed to the tree over there;” one scarred by fire, Isaac’s dad said. “He said, ‘It looks like it’s had its skin burned off.’ I said, ‘It’s not skin, it’s bark.’ And he was like, ‘Oh, yeah, bark.’”

“It was a great father-and-son moment.”

mike.anton@latimes.com