Equestrians Mount a Drive for More Public Trails : Recreation: Riders calling for greater access to the Santa Susanas say they have nowhere else to go because of rapid growth in the county.

Those who enjoy saddling up old Swayback for a gallop through San Fernando Valley canyons used their collective horsepower this weekend to launch a campaign aimed at opening more public riding trails.

Members of Equestrian Trails Inc., which sponsored a four-mile ride from O’Melveny Park in Granada Hills to a ridge top in the adjacent Santa Susana Mountains, say rapid growth in once-rural areas of northern Los Angeles County has prompted their call for the purchase of more public lands.

“Horse people are starting to concentrate efforts because we realize there is nowhere else to go,” said Ann Irvine, a Newhall resident and spokeswoman for the group active in the Santa Clarita, Antelope and San Fernando valleys. “The nearest trails are two and three hours’ drive away.”

Irvine said the organization intends to join with hikers and mountain cyclists to push for greater public access to the Santa Susana Mountains.

About 50 horseback riders ascended the mountains rising from O’Melveny Park, which is at the northern tip of Granada Hills, and traveled through portions of the 6,000 acres proposed for inclusion in the Santa Clarita Woodlands State Park.

The southern face of the mountains is an arid landscape most of the year. But the northern side is a dense woodland that includes valley oaks, big-leaf maple and big-pine spruce. Access to many trails and dirt roads north of O’Melveny Park is blocked by locked gates controlled by private landowners.

The riders were blocked Saturday from crossing to the northern side of the mountain range by a locked gate, a literal example of the barriers horse enthusiasts encounter in the Santa Susanas.

Conservationists are battling county sanitation officials who are interested in using canyons in the area for dump sites to ease the county’s mounting garbage problems.

The Santa Monica Mountains Conservancy, a state agency that acquires land for parks, believes that the area should be purchased from its various landowners and held for public recreational use.

The conservancy a year ago bought 145 acres of pristine woodland in Towsley Canyon as part of the planned Santa Clarita Woodlands State Park.

If realized, that park would become part of the Rim of the Valley Trail Corridor that the conservancy is trying to create. The trail would encircle the San Fernando Valley.

State parks and recreation officials said last month that it would cost about $44 million to buy land proposed for the Santa Clarita Woodlands State Park from 94 owners. Because there is no state money for the purchase, it will probably take 10 years to buy the land, officials said.

In a study released last month, the area has been identified as environmentally significant and worthy of state protection.