It took Mountain House 20 years to go from zero residents to 20,000.

River Islands at Lathrop, at its current pace, will reach that benchmark in 12 years.

As of last week, there were 2,007 homes occupied on the Delta island with the given name of Stewart Tract. Four years ago the planned community’s first families were just starting to move into new homes.

Based on the typical household occupancy, that reflects 7,024 residents. It is a quarter of Lathrop’s overall 28,000 plus residents.

The two communities give a stark look at the growing wave of new residents South San Joaquin County is luring from the Bay Area with its job rich economy dealing with not just a housing shortage but selling prices and rents are among the highest in the nation.

Growing at roughly the same 500 plus pace of new homes are also neighbors of the two planned communities — Tracy and Manteca.

River Islands, unlike Mountain House, is part of a city. The rest of Lathrop is also experiencing strong residential growth.

Mountain House nestled at the base of the Altamont Hills and along the county line is exploring become San Joaquin County’s 8th incorporated city. It is to the northwest of Tracy.

River Islands started building its first home in 2017, As of last week 2,500 of the planned 15,000 housing units have been sold. There are seven builders actively selling and two more that are closed out and finishing up sold homes.

More housing developments are moving forward including the much anticipated Del Webb at River Islands.

 Del Webb at River Islands will consist of 900 single-story homes ranging from 1,450 to 2,765 square feet with two and three bedrooms.

The age-restricted active adult community for those 55 and older will include a recreation center featuring a swimming pool, fitness center, bocce courts, tennis courts, and pickleball courts. The neighborhood is expected to open in late 2022.

River Islands is also getting ready to move forward with their initial apartment complexes next year. Cambay Group intends to retain ownership of all apartment complexes in River Islands to assure they are operated and managed in accordance with the goals of the planned community.

River Island President Susan Dell’Osso said the intent is to design complexes that dovetail into how River Islands is developing town centers, a transit village on the future Valley Link commuter line, and a commercial area on the island’s southern side.

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com