Hollywood stars are trying to save their Malibu beach homes from being washed into the ocean by buying $20 million worth of sand — but they’re getting thumbs down from environmentalists. Dustin Hoffman, Steven Spielberg and Ray Romano are among the owners of 114 houses (average price $7.8 million) on Broad Beach, which needs a new name after decades of erosion wiped out dunes and left a narrow strip of sand between their houses and the surf, writes The Post’s Richard Johnson. The influential group also includes former CAA superagent Mike Ovitz, entertainment lawyer Marshall Grossman and “Modern Family” co-creator Steven Levitan, who told The Hollywood Reporter, “We can’t imagine there being a negative impact to restoring the beach to its former self. Here we are, taking this project on, doing something that will provide great benefit to the public in an incredibly environmentally sensitive way, and we’re not asking for one penny of taxpayer dollars. It’s a no-brainer.” Ken Ehrlich, the lawyer representing the homeowners, has already found the sand. “Ventura Harbor, one of the top ten commercial ports in the country, needs dredging, and there are no funds for it,” Ehrlich told us. “We are offering to dredge the sand for them. It’s a win-win.” No fewer than nine federal, state and local governments have to issue permits before the work can begin. ” But some environmentalists are against any beach-protection measures, be they sand, rock, or bulkheads. They think the homeowners should either retreat from the beach or raise their houses on stilts. As for the buried septic tanks that are now almost exposed, the environmentalists suggest the homeowners convert their plumbing to the dry-composting, water-less toilets being pushed in the Third World. Grossman is baffled by the resistance. “I can understand objections if we were unleashing wild animals or placing nuclear waste on the beach,” he said. “But sand? Give us a break.”