They are talking about closing the creek crossing, not the dunes. Here's an article from the local paper:
Tue, Jun. 14, 2005
Looking at new routes to Dunes
Environmentalists want Arroyo Grande Creek crossing avoided altogether; the state will decide if alternate routes are feasible
The state Parks and Recreation Department is taking a fresh look at one of its thorniest environmental problems in San Luis Obispo County -- access to the Oceano Dunes State Vehicular Recreation Area.
Every year, thousands of cars and trucks enter the beachfront park to drive dune buggies and all-terrain vehicles on the sand. All of these vehicles drive through Arroyo Grande Creek.
This is unpopular with some environmentalists because the creek is habitat for steelhead trout, a federally listed threatened species.
Ponds upstream of the beach contain tidewater gobies, another threatened fish, said Andrew Christie of the Sierra Club.
"You have vehicles crossing five abreast stirring up the river and tow trucks pulling cars out," Christie said. "There is a lot of impact on that creek."
The state Parks Department has hired a Santa Barbara consulting firm, Condor Environmental Planning Services, to look at new routes for vehicles to enter the popular park. The study should be completed next summer.
"We've put everything on the table to find out what would be the best access, including the present access points," said Ray Monge, deputy district superintendent for state parks.
Horse riders also enter the park across the creek from Silver Spur Place. Alternative access routes near 22nd Street and an oil refinery on the Nipomo Mesa, among others, will be examined.
The Parks Department has examined alternate access before, and found that building a new route would have adverse environmental consequences of its own, including habitat destruction.
Officials agreed to take a fresh look at the problem late last year when the department settled a Sierra Club lawsuit over impacts of human activities on several rare and endangered species in the park.
Environmentalists want creek crossings avoided altogether.
The Parks Department will use environmental study findings to decide if alternate access routes are feasible and where they should be located.