River Islands at Lathrop sales are picking up steam.

Last weekend the four builders each sold two homes apiece. That brings the number of homes sold to date to just over 300.

But the big surprise for Susan Dell’Osso, the project manager for the 11,000-home planned community, is who is buying the homes.

A third of the purchasers are move-up buyers from Manteca and Lathrop, a third are from Mountain House and Tracy, and the remaining third are Bay Area buyers.

“It’s great,” Dell’Osso said. “Not only that it is the local buyers (Manteca, Lathrop, Tracy, and Mountain House) that are buying the more expensive homes while Bay Area buyers are buying the less expensive models.”

The expectation was that Bay Area buyers would make up the bulk of the buyers.

Currently River Islands sales are leading home sales in the South County.

In Manteca, the city’s two leading traditional single family home builders — Raymus Homes and Atherton Homes — have virtually sold out of existing lot inventory and are getting ready to break ground on new lots. Raymus is doing so along Woodward Avenue between Union Road and Airport Way. Atherton is moving forward with more lots along Pillsbury Road south of Woodward Avenue.

Toni Raymus noted her firm has had to deal with issues that other builders have had as well such as an unexpected shortage of windows and such. Even so,

Raymus has been averaging two home sales a week while Atherton has sold between one and two on average.

Most of the Raymus buyers are still local from the Northern San Joaquin Valley while Atherton is starting to see more Bay Area buyers than local.

And while 2015 has been good the perception among some builders was that it would be even stronger. That, however, may be simply a matter of timing.

“We should see more activity as the Bay Area housing market continues to heat up,” pointed out Bill Filios, a principal with Atherton Homes.

River Islands is designed as a community with a built-in lifestyle with relatively small lots. Atherton Homes tends to sell larger homes on larger lots while Raymus falls in between.

Dell’Osso said River Islands is getting ready to release another 400 lots to builders.

Cambay Group is in position to develop another 1,000 lots in 2016.

At the same time they expect to extend the system of super levees — so dubbed for their 300-foot width to significantly enhance their exposure to 200-year floods — by 2018 to create more buildable lots.

Meanwhile, there is a growing waiting list for the prime lots at River Islands — 900 honesties that will sit atop the strengthened levees that will surround the planned community along with a greenbelt open to the public.

There are 100 potential buyers on the list.

“We may release a few next year, we’re not sure,” Dell’Osso said.

The lots are considered potential “million dollar views” given lots overlooking the San Joaquin River for homes are essentially non-existent.

Dell’Osso said the bulk of the custom lots will be released as development of the project moves further down the road.