The hill at Sand Dune Park in Manhattan Beach is quiet. A shred of yellow caution tape flutters near the top of the dune. Partway down, a sign on a crooked pole directs children to the left, adults to the right. But no one visits the slope any more.

The sand dune, which attracted thousands of visitors who ran up and down the soft hillside in pursuit of the ultimate cardio workout, was fenced off in August amid concerns about erosion and years of complaints from residents about noise, litter and traffic.

Now, residents say they can enjoy their neighborhood again without fear of dodging speeding traffic or cleaning up discarded water bottles and litter.

“It’s like the end of a storm,” said Bob Sandus, 65. “It’s nice to have peace.”

But the dune detente may be coming to an end. The city is weighing whether to reopen the mammoth pile of sand.

For years, the tiny city park -- which is in a neighborhood blocks from the beach -- has been a mecca for workout buffs who walk or run the dune, the soft, shifting sand an alluring, muscle-burning test of agility that aficionados say is easy on the joints.

Laker stars Kobe Bryant and Andrew Bynum are among the athletes who have trained there. But some residents say the park was meant to be a play space for neighborhood children and has been hijacked from its original purpose.

Sandus said he was among the residents who helped build the park. The retired engineer recalled digging holes with his neighbors decades ago to plant mulberry, pine, eucalyptus and sandalwood trees around the park. His children’s birthdays often were celebrated around the dune, he said.

But, over time, as the dune gained popularity through word of mouth and the media, the number of visitors exploded. Basketball and football teams arrived by the busload to train in the sand. Even some dune climbers eyed the crowds on the hill and the sunbathers at the foot of the dune, and wondered whether closing the hill was a bad thing.

“It just got ridiculous,” said Maribel Valdez, 42, who walks the approximately 200 steps next to the hill now that she can’t use the dune itself. “A lot of people were complaining about how crazy it was,” she said. “You couldn’t have your own privacy -- people couldn’t get out of the way.”

Erosion became an issue. The city was paying as much as $4,500 each time it rebuilt the dune.

In July, Councilman Richard Montgomery said there were 9,000 visitors to the dune, three times the peak crowd from a decade earlier. “It was destroying the dune,” said Richard Gill, the city’s director of parks and recreation. “There’s not a blade of grass left down there.”

But the loss of the dune has come at a cost to others.

“There’s been no area in all of South Bay that has been so successful for so long at motivating people to exercise regularly,” said Bill Hory, a Manhattan Beach resident who is pushing for the city to reopen the dune. “It seems perverse to completely shut down a place like that.”

A Facebook group called Save Sand Dune Park has grown to 1,600 members, and around 1,200 people have signed a petition, about 450 of them Manhattan Beach residents, Hory said. Some plan to gather at the beach later this month and march to the dune to protest its continued closure.

City Council officials say they are considering multiple options, from creating a permit that would allow a limited number of people on the dune at one time to shortening hours or installing parking meters.

There also are proposals to landscape part of the dune and leave an area just for children to play.

amina.khan@latimes.com