A World War II naval weapons base is gearing up for a transformation into one of the largest mixed-use redevelopments underway in California as the state looks to increase housing to offset rising prices that have contributed to a population decline in recent years.

New York real estate investor Brookfield Properties won an initial green light from the city of Concord to build more than 12,000 houses and 6 million square feet of commercial space at the Concord Naval Weapons Station, a former military base northeast of San Francisco, where tight housing supply and the resulting lack of affordability is seen as a barrier to entry. The city's population fell 7% from the start of 2021 to the end of 2022, the highest loss in California by a wide margin.

Brookfield said it will build 3,050 residences priced below 80% of the area median income as part of the planned project over the next four decades at the 2,300-acre base that's owned by the United States Navy. Brookfield aims to take ownership of the site within the next four years, according to a non-binding term sheet approved in the past week by the Concord City Council.

After it takes ownership, Brookfield will seek final planning department and city council approvals before beginning construction.

The investor emerged as the sole bidder for the contract last year after similar proposals with other developers — including Miami-based Lennar and California-based Concord First Partners — fell through. The city has been considering alternative uses for the base since it closed in 1999.

Brookfield's plans call for 12,200 houses, 880 acres of parks and other green space alongside offices, shops, restaurants and schools over five phases of development.

In a public meeting regarding Brookfield's proposal, city Mayor Edi Birsan noted Brookfield was one of few for-profit developers to propose affordable housing, or homes priced between 30% and 80% of the area median income, in Concord.

“I want affordable housing built; I don’t care who does it,” Birsan said. “I don’t like the idea of a monopoly on affordable housing. I like the idea of our good friends at Brookfield sticking their necks into the business.”

The project is larger than several other notable mixed-use developments in the works in California, a state that lost 37,203 last year, make for its fourth consecutive year of losses.

Across the bridge in Santa Clara, one of the South Bay’s largest cities, Related Cos.’ California division is working to build 1,700 housing units and 15 million square feet of commercial space near Levi's Stadium, the home of the San Francisco 49ers.

The developer has a similar project in the planning stages in Southern California's affluent Orange County region, where it plans to develop 3,750 residential units, 350,000 square feet of retail and 250 hotel rooms at its Related Bristol development.

Related said in city filings that both projects will include affordable housing.

Elsewhere in Southern California's San Diego, Houston-based Hines Global Trust recently began construction on its Riverwalk development, a $4 billion mixed-use redevelopment of a 200-acre golf course into 4,300 homes as the city looks to boost its affordable housing supply, with at least 10% of the units to be reserved for individuals earning less than 80% of the area median income.

Silicon Valley tech giant Google once envisioned building several real estate projects across the Bay Area totaling 15,000 housing units and millions of square feet of commercial space in a partnership with Australian developer Lendlease, but the duo dissolved the pre-pandemic deal last year.

Google said it still plans on moving forward on the proposals, either through a new agreement with Lendlease or a different firm, though it has yet to share specifics.

Concord has just north of 11,000 apartment units, according to CoStar data, compared to the nearly 50,000 apartment units in Oakland, the East Bay's largest city by population with 420,000 residents. Concord has a population of roughly 124,000.

Developers have built just 1,000 apartment units in Concord over the past two decades, during which the city's population has increased by 56,000 residents, according to Census data.

Mixed-use projects in growing cities like Concord are on the rise due to consumers' evolving demand to live in centralized communities, according to a report by JLL. Changes to work trends brought on by the COVID-19 pandemic have only increased the interest in these types of developments.

“Demand for experience-driven developments is likely to increase further in the coming years,” said Julia Georgules, vice president and director of local research markets at JLL. “It’s a natural extension of the emphasis on inspiring workplaces in the U.S. People are learning they can get more out of their offices, as well as their neighborhoods which ultimately helps both business and communities.”

New York City's Hudson Yards is billed as the largest U.S. private real estate development with office space alongside an Equinox hotel and residential towers as well as retail shops, restaurants and tourist attractions such as the popular Edge observation deck.

In the Midwest, developer Sterling Bay is building another mixed-used community along the Chicago River that includes 6,000 units of housing and commercial space.