DEL MAR, Calif.—More than 1,000 people turned out Monday at a public hearing over a proposed toll road that would pass through one of Southern California's most popular parks and near a world-class surf break.

Until now, the fight over the road—which would cut through San Onofre State Beach and end a half-mile from the surf break Trestles—has focused on its environmental impact.

The California Coastal Commission rejected the plan in February after environmentalists and other opponents argued that the 16-mile, six lane road would wipe out several endangered or threatened coastal species, decimate an ancient Indian burial ground and block sediment that creates world-class waves at Trestles.

But the company that hopes to build and finance the proposed $1.3 billion road, the Transportation Corridor Agencies, appealed that decision to the National Oceanic & Atmospheric Administration, a branch of the U.S. Commerce Department. It hopes to get the state's decision overturned by arguing that the road would play a key role in national security and economic growth.

So many people signed up to speak at NOAA's hearing Monday—more than 650—that it scheduled the meeting at a fairgrounds to accommodate the crowd and hired security officers to help maintain order. Officials expected to make it through less than a quarter of those speakers before the end of the 10-hour hearing, and most of those were to be elected officials.

Even so, more than 1,000 people packed into the space by the start of the hearing, many wearing T-shirts that read either "Save the Park, Stop the Toll Road" or "241: Less Traffic, More Jobs." Audience members—who frequently interrupted the speakers with cheers or boos—were urged to instead give a thumbs-up or thumbs-down sign to indicate their feelings.