A California senator and congresswoman Thursday introduced legislation to permanently protect 191,000 acres of Riverside County wild lands.

The California Desert and Mountain Heritage Act, authored by U.S. Sen. Barbara Boxer and Rep. Mary Bono, R-Palm Springs, would create four new wilderness areas, expand six existing such areas and designate 31 miles of county streams as "wild and scenic rivers."

The designations would bar development and motor vehicle use, while allowing hiking, hunting and horseback riding.

One of the existing wilderness areas is the 16,000-acre Agua Tibia along the north slope of Palomar Mountain southeast of Temecula, where groves of pine and fir in shaded canyons shelter rare Mexican spotted owls. The area is targeted for a 2,000-acre expansion.

The measure also would create a new 16,000-acre Beauty Mountain Wilderness off Highway 371 east of Temecula and wrapped around a 5,548-foot peak, as well as a new 7,000-acre Cahuilla Mountain Wilderness near Anza.

Elsewhere, it would expand and create wilderness areas in the heavily forested San Jacinto Mountains around Idyllwild, in Joshua Tree National Park and in the desert foothills around Palm Springs.

Environmentalists, university officials and local business groups applauded the measure.

Geoffrey Caine, first vice president for the Idyllwild Chamber of Commerce, said, "People from across the country have come to this area for years, drawn by Lily Rock. But now these beautiful wild lands will provide additional protected spaces to promote as environmental destinations."

Mike Hamilton, director of the UC Riverside James Reserve in the San Jacinto Mountains, said the measure also will help promote the long-term welfare of rare and imperiled plants.

"Some of the areas protected … contain plants and other species at the far southern end of their range, and even some that exist nowhere else on earth," Hamilton said.

The measure is designed to provide places of refuge for such imperiled animals as the Quino checkerspot butterfly, Peninsular bighorn sheep and desert tortoise.

But Meg Grossglass, a French Valley resident and spokeswoman for the Off-Road Business Association, said motorcycle and all-terrain-vehicle riders tend to get nervous when sweeping wilderness proposals such as this one surface. That, she said, is because past wilderness bills have locked up trails that off-roaders had enjoyed for years.

"There are just so few left here in Riverside County," Grossglass said.

There is always a risk with each new wilderness proposal, she said, that frustrated off-roaders will respond by riding illegally where they are not supposed to.

"We don't condone that," Grossglass said. "But the people who have vehicles are going to find a place to ride."

She said Riverside County has 96,000 licensed off-highway vehicles, third most in the state behind Los Angeles and San Diego counties. And she said the owners of those vehicles need an adequate number of places to legally practice their favorite sport.

"Most off-roaders do believe that there are appropriate places for wilderness, but we need to be very careful about where we designate them," Grossglass said.

Besides expanding Agua Tibia Wilderness and creating two new wilderness areas in Southwest County, the measure would add 78,000 acres to existing wilderness in Joshua Tree National Park and create a 22,000-acre South Fork San Jacinto Wilderness near Idyllwild. The legislation also would protect unspoiled sections of the North Fork of the San Jacinto River, Bautista Creek, Fuller Creek and Palm Canyon Creek.

Readers may view maps at www.desertmountainwild.org/lands_rivers.html.

Contact staff writer Dave Downey at (951) 676-4315, Ext. 2623, or ddowney@californian.com.