San Diego Gas & Electric Co.'s proposed Sunrise Powerlink transmission line would ruin a largely unspoiled area of waterfalls, oak forests and granite gorges that crowns a river park and trail system being developed between the ocean and Julian, the head of a conservation group said Tuesday.

As a result, the nonprofit group working to develop the San Dieguito River Park and the associated 55-mile Coast to Crest Trail is lobbying SDG&E to shift part of its "preferred route" through the San Diego County mountains, said Craig Adams, executive director of the San Dieguito River Valley Conservancy.

Adams said the group worries that the Santa Ysabel Ranch area, with its 200-foot cliffs, 50-foot cascades, golden eagles and abundance of rare plants, will be ruined.

"This area is, I think, one of the most beautiful areas along the Coast to Crest Trail," Adams said.

And Santa Ysabel is an ideal spot for a resting/picnicking facility for hikers and horseback riders, he said.

"It has water," Adams said. "It has wonderful oaks and shade. It has plumbing and wells because it was a ranch."

Stephanie Donovan, a spokeswoman for SDG&E, said Tuesday that the utility is reviewing those concerns and will address them in the environmental report it plans to file with the California Public Utilities Commission on Aug. 4. The state regulatory agency is expected to decide the fate of the proposed power line sometime next year.

Donovan said the report will unveil changes to the utility's original $1.4 billion proposal, but she stopped short of saying whether those would affect the route through Santa Ysabel.

"This is certainly not set in stone," she said. "I think we are probably going to see a few changes in the route."

SDG&E is proposing to string wires from erector setlike-towers as tall as 160 feet for 120 miles through Imperial County and the backcountry of San Diego County, and ultimately tie them into a Carmel Valley substation. The wires would create a different skyline for residents along the edges of urban areas, while sections would be buried in Ramona and Rancho Penasquitos.

SDG&E, which serves 1.3 million homes and businesses in San Diego County and southern Orange County, says its customers need the 1,000 megawatts the transmission lines would be able to carry. Business leaders said Monday that the additional electricity is needed to keep San Diego County's $160 billion economy humming.

Project opponents don't dispute the need for more electricity, but say there are better, less expensive ways to plug a looming power shortfall.

The conservation group and a public agency, the San Dieguito River Park Joint Powers Authority, have been working for two decades to piece together an open-space park extending from 5,575-foot Volcan Mountain near Julian to the sea at Del Mar. Adams said that 75 percent of the 80,000 acres targeted for the park have been obtained and trails are in place for half of the 55 miles.

During the last six years, he said, public agencies and the conservancy bought key blocks between Lake Sutherland and Santa Ysabel Ranch, in part with $15 million in state bond money. Adams said it is those additions that are at risk because of SDG&E's project.

"The line would be just to the east of where the (Santa Ysabel Creek) gorge starts," he said.

The authority, composed of the county, Del Mar, Escondido, Poway, Solana Beach and the city of San Diego, also opposed the route. In a letter dated May 2, Jerry Finnell, authority chairman and Del Mar councilman, wrote that the towers and access roads to them would exact "significant visual impact to this pristine landscape."

In a June 28 letter, Tom Golich, conservancy president, called the preferred route "unacceptable" and suggested that SDG&E move the line to Highway 79 and bury it.

If the wires can't be put underground, said Adams, the next best option would be to build towers along the base of a mountain range to the east, where they could be shielded from view.

"We are taking into consideration their suggestions and concerns," Donovan said. "We hope to be able to address some of their concerns in the ultimate preferred route that we include in our filing on Aug. 4."

- Contact staff writer Dave Downey at (760) 740-5442 or ddowney@nctimes.com.