Closing a 4.4-mile gap in Highway 39 above Azusa in the San Gabriel Mountains will present steep engineering and environmental challenges, officials from Caltrans and the state Department of Fish and Wildlife said Monday at a meeting in El Monte, not to mention a cost that could reach $100 million.

Despite the obstacles, both Rep. Grace Napolitano, D-El Monte, and Los Angeles County Supervisor Kathryn Barger pushed for the project — both had just taken helicopter tours of the damaged state highway which was washed away in a rain storm and abandoned by the state nearly 40 years ago.

“It is about access to the forest, access to public lands,” Barger said during the after-tour roundtable at San Gabriel Valley Airport in El Monte.

Barger’s comments were in response to a flurry of concerns from Shirley Casas Choate, chief deputy district director of Caltrans in Southern California. During the ride, Choate said the poor condition of the road and sediment falling from the crumbly mountains could undermine any new roadway or culvert during a heavy storm.

“We would have to restore the structural integrity of the road,” she told the group.

Napolitano said she believes Caltrans is capable of widening the closed section — which now functions solely as a narrow shoulder for emergency vehicles only — into a two-lane highway for the public to drive, once again connecting with Angeles Crest Highway and continuing a loop from the San Gabriel Valley to Wrightwood and local ski areas.

“So a $100 million price tag doesn’t scare you?” asked Choate, who later said the amount could be between $40 million and $100 million. Caltrans will complete a preliminary study in March, which could trigger a full environmental review.

In addition to the conditions of the roadway, about 500 Nelson’s bighorn sheep will also present challenges to any work in the area. The sheep roam from Lytle Creek near I-15 across the San Gabriels and into the national monument area.

The rebounding and “fully protected” sheep population can’t be killed per state law, said Rebecca Barboza, environmental specialist with Fish and Wildlife, who attended the meeting.

While Napolitano asked the state to find ways to not harm a single sheep, Barboza implied it wouldn’t be that easy. For example, during construction, crews would not be allowed to use nets that catch boulders loosed by excavation — the sheep’s horns could become entangled in the netting.

Also, Barboza was concerned that the area where the road would be expanded, a remote region 6,200 feet in elevation west of Wrightwood called Islip Saddle, is also where the sheep’s lambs are born. Disruption of lambing season would be strictly prohibited, she said.

Barboza said the department knew very little about the sheep population in the San Gabriel Mountains National Monument.

The department was given a grant of $8,000 by Caltrans to attach radio collars to 30 ewes to track their whereabouts and birthing locations. But the sheep tracking won’t start until 2019, she said, due to a shortage of staff and funding.

Choate said that the state could amend its program organizing highway repair projects to include a Highway 39 gap-closure project. But the full amount could take years to acquire as other projects are more urgent.

“It is a matter of justifying the priority,” she said.

In 2009, Caltrans committed to the project at a cost of about $32 million. Work was about to begin in 2011, but at the last minute the money went toward repairing a bridge on Highway 1 in Northern California.

“State Route 39 is a low-volume, Class 3 highway and the reopening project would not be able to compete for limited (state) funds with other projects on high-volume corridors within the state highway network,” Carrie Bowen, Caltrans district director, told the city of Azusa in February 2016.

The final segment of Highway 39 was built in 1957 on the order of Pres. Dwight Eisenhower and remained complete until 1978. During those years, about 800 cars per day used the high country segment, Choate said. If completed, Caltrans estimates the road would see about 2,900 automobiles per day.

Jeff Vail, supervisor of the Monument and Angeles National Forest, suggested that instead of a full-access highway to Highway 2, shuttle could ferry visitors back and forth.

Azusa Interim City Manager Don Penman and Azusa Chamber of Commerce Executive Director Steve Castro agreed to hold public meetings to gauge local support for some kind of access into the closed section of Highway 39, beyond Crystal Lake recreation area and campground, which is located about 22 miles north of Azusa.

“My only concern is to keep the process moving,” Penman said.