ANTIOCH — Dozens of seniors flocked to City Hall on Tuesday urging council members to prevent the owners of their mobile home park from opening it up to all ages.

Residents of the 150-unit Vista Diablo Mobile Estates packed the council chamber, fearful that their rents might spiral and quality of life suffer once the owners’ 10-year agreement to preserve the facility as a predominantly senior community expires in October.

Located on Somersville Road, the mobile home park has required at least one person in each unit to be 55 or older since it began operating in 1978.

And that’s just how Larry and Vivian Espinoza thought it would stay when they moved in about eight years ago, unaware of the temporary deal their landlord had made with the city.

A mobile home park designed for seniors isn’t well-suited to young families, argues Vivian Espinoza, 74.

The collection of two-bedroom houses have tiny front lawns and equally small backyards, so youngsters often amuse themselves in the streets, residents say.

“You’ve got children running around — there’s no place for them to play,” Espinoza said before the meeting, noting that the park doesn’t have a playground. “And there’s more vandalism. Teenagers get bored and they vandalize.”

Younger residents also disturb the peace, driving through the park with loudspeakers blasting, Espinoza said, adding that one couple was caught having sex in an elderly woman’s storage shed.

Like his neighbors, 78-year-old Jerry Coffel is bothered by noisy children like the preschooler across the street whose shouting he can hear from inside his home.

“As seniors you’re entitled to quiet habitation of your house,” the 17-year resident said. As more youngsters and their parents move in, “the whole tenor of the park changes.”

Many who spoke at Tuesday’s meeting also cited concerns that the wholesale acceptance of younger working couples who can afford higher rents will drive up housing costs for everyone, forcing out those living on fixed incomes.

Coffel and others are urging the city to adopt an ordinance establishing a so-called “senior mobile home overlay zoning district,” which would ensure that Vista Diablo Mobile Estates remains largely a senior community.

Although federal housing law prohibits discrimination on a wide variety of fronts, an amendment in the 1980s allowed landlords and developers to restrict housing to seniors as long as that demographic comprised at least 80 percent of the complex’s units.

Cities also began citing this exception to create residential zoning that allowed only senior housing, preventing enclaves of elderly residents that already existed from converting to “all-age” communities.

Over the last few years, 22 California cities from Huntington Beach to Hayward as well as Fremont, San Jose and Sunnyvale have adopted senior mobile home overlay zoning districts, said Karilee Shames, zone vice president for the Golden State Manufactured-Home Owners League.

Because it appears that the vast majority of Vista Diablo Mobile Estates’ residents are seniors, council members responded to their impassioned pleas by unanimously agreeing to consider adopting an urgency ordinance at their July 11 meeting.

The ordinance, if approved, would establish an immediate moratorium on any changes to the mobile home park’s residency requirements while city officials study the matter further and come up with a permanent set of rules.