AMNA NAWAZ: Cities worldwide are overcrowded, overpriced and a source of global warming.

The dream?

Build a livable, affordable, eco-friendly community.

Paul Solman went to California to see the plans for one of those big dreams.

But there's plenty of skepticism about that vision and the developers behind it.

NARRATOR: The Line will be home to nine million residents.

PAUL SOLMAN: Want a brand-new dream city built?

How about The Line in Saudi Arabia?

NARRATOR: The Line is 500' meters tall, 200' meters wide.

PAUL SOLMAN: No cars, no carbon emissions, designed to host a population of nine million.

Well, maybe someday, maybe not.

But a lot closer to home and perhaps to reality, there's now California Forever, a planned cutting-edge community that has gobbled up 60,000 acres of farmland in Solano County, an hour north of San Francisco.

JAN SRAMEK, CEO, California Forever: We're building a new community in the Bay Area.

PAUL SOLMAN: CEO Jan Sramek.

JAN SRAMEK: That's going to make it possible for a new generation of Californians to realize the California dream, the way that prior generations have been able to do it.

RONALD KOTT, Mayor of Rio Vista, California: This is the footprint that they're presenting.

PAUL SOLMAN: Here's how the new community depicts itself in the plans it showed Ronald Kott, mayor of Rio Vista, population 10,000, which borders the 60,000 acres.

RONALD KOTT: Surrounding communities kind of come here, do other restaurants and shopping and that kind of thing and... PAUL SOLMAN: Pedestrians.

RONALD KOTT: Pedestrian, but everything is walkable.

PAUL SOLMAN: Housing for 50,000 to start, as many as 400,000 people eventually, with condos a lot cheaper than anything you can get in and around San Francisco, 18,000 acres for the town, another 21,000 for a solar farm to power it with energy to spare.

BRONSON JOHNSON California Forever: We're in the heart of the new community.

This will be medium density, urban form blocks of housing and our downtown will be just a little bit this way from where we're standing today.

PAUL SOLMAN: Bronson Johnson of California Forever.

BRONSON JOHNSON: When you're starting from scratch and you're building new water recovery plants and new energy plants, this can be entirely renewable and a sustainable model for the rest of the world to follow.

PAUL SOLMAN: In order to expand the project eventually, the group has made a series of legally binding promises, to create 15,000 new jobs, spend $30 million to protect local ecosystems, and allocate $400 million for housing assistance.

JAN SRAMEK: Homes that families can afford in safe and walkable neighborhoods.

PAUL SOLMAN: Moreover: PRINCESS PALMER, Real Estate Agent: It gives people a chance to build generational wealth.

PAUL SOLMAN: A historical problem for Black people, says local real estate agent Princess Palmer.

PRINCESS PALMER: A lot of times, it's the down payment and the closing costs that prevent people from being able to buy here in California.

So that would be an amazing opportunity that you just don't see right now in California.

PAUL SOLMAN: Another local, Alix Pate, likes the project for a different reason.

ALIX PATE, Solano County, California, Resident: I have small children, a 3-year-old and a 1-year-old, and I have these concerns of, where will they live and is there going to be housing for them when they are ready to buy?

PAUL SOLMAN: So, the project seems pretty unobjectionable, right?

Well, of course not.

There have been objections galore, like at this town hall meeting.

MAN: How do you expect anyone in this room or the county to believe what you're saying?

PAUL SOLMAN: For years, a firm known only as Flannery Associates quietly amassed tens of thousands of acres in Solano County, and no one knew why.

Only last August did The New York Times report that Flannery was backed by Silicon Valley billionaires, which CEO SRAMEK now acknowledges.

JAN SRAMEK: Our main investors are a group of Californians who have decided to double down on the state.

They include Laurene Powell Jobs, John Doerr, Michael Moritz, Marc Andreessen, and the venture fund Andreessen Horowitz.

PAUL SOLMAN: And Sramek only first appeared before locals in November.

Locals didn't like the secrecy and also worried about the strains that come with development, like water depletion.

CATHERINE MOY, Mayor of Fairfield, California: Every drop of water in this county is taken.

PAUL SOLMAN: Catherine Moy, mayor of Fairfield, abutting the project: CATHERINE MOY: They do have some water that they have from the land that they bought, OK?

It's not enough for a city.

It's not enough for that.

So they say they're going to buy water from elsewhere.

OK, well, I bet they might.

But I don't think it's going to be enough.

PAUL SOLMAN: But, says CEO Sramek: JAN SRAMEK: We have a water guarantee for every single building we build, whether it's an office building or a manufacturing facility or a home.

We have to prove that we have enough water for many, many decades, including through drought periods.

KATHLEEN THRELFALL, Solano County, California, Resident: This is my grandfather and one of his pals.

PAUL SOLMAN: A little ways down the highway, rancher Kathleen Threlfall now tends the property purchased by her great-grandparents.

KATHLEEN THRELFALL: When I come down the road, it's what everybody in the world wants.

It's like the whole relaxation experience.

I'm home and this is my place.

PAUL SOLMAN: And how long are you going to stay here?

KATHLEEN THRELFALL: Probably until I drop off the tractor or something.

(LAUGHTER) PAUL SOLMAN: So offers to buy her 243 acres, starting at $2 million, now up to 4.5, were nonstarters.

KATHLEEN THRELFALL: They have tried to buy my land.

I have said no.

PAUL SOLMAN: Why?

KATHLEEN THRELFALL: Why?

PAUL SOLMAN: Yes.

(LAUGHTER) KATHLEEN THRELFALL: This is my spot.

PAUL SOLMAN: There's the phrase we all know, NIMBY, not in my backyard.

KATHLEEN THRELFALL: Right.

God, I hate the idea of being a NIMBY.

I really do.

PAUL SOLMAN: Well, but that's what you are, no?

KATHLEEN THRELFALL: But that's what I am.

That's what I am in this case.

PAUL SOLMAN: Yes.

KATHLEEN THRELFALL: I mean, this case, I'm saying, this is not a good idea in this particular place at this time.

CATHERINE MOY: I don't like being called a NIMBY either.

PAUL SOLMAN: Again, Mayor Moy.

CATHERINE MOY: I'm just a person who grew up here, love this area, and this is upending all of that.

PAUL SOLMAN: There's one other big issue, the lawsuit.

IAN ANDERSON, Solano County, California, Resident: We have spent more on this lawsuit than what it would cost to get our kids through school.

PAUL SOLMAN: That's a half-a-billion dollar suit against landowners who refuse to sell, claiming they colluded to inflate the price.

Ian and Margaret Anderson and even their distant family members have been forced to defend themselves.

MARGARET ANDERSON, Solano County, California, Resident: They just pulled those family members in as well, I think just as a strong-arm tactic to frighten people to sell their land.

PAUL SOLMAN: The CEO's version: JAN SRAMEK: We made an offer to the Andersons.

They made a counteroffer where they asked for a very high price.

We said, no thank you.

We don't want to buy the property at that price.

And the lawsuit alleges that, after that, they organized this price-fixing conspiracy in order to force us to pay the higher price.

PAUL SOLMAN: So have you guys been colluding with other people to jack up the price?

IAN ANDERSON: I have been a farmer in this area for 67 years, and I have never done any colluding in that realm any way, shape or form.

PAUL SOLMAN: As to the discussion of selling, given the cost of the suit, it was and remains a painful one.

MARGARET ANDERSON: It's amazing what a person considers doing when they are being asphyxiated.

And that's what we felt was happening.

There were many discussions between us about what's the right thing to do.

Do we do what's right for us and plant our heels?

Or do we think about the possibility to provide for our son in the future?

PAUL SOLMAN: And to keep the tradition going?

MARGARET ANDERSON: Keep the family operation going.

PAUL SOLMAN: But there must be a price at which you would sell, no?

IAN ANDERSON: I will take a little bit of offense to that, because I wake up each morning looking forward to the farm day growing crops.

RONALD KOTT: I think there are some opportunities for our city.

There are some warning signs for our city too.

PAUL SOLMAN: As mayor, Kott is in favor of economic growth, as a resident who treasures where he lives, not so sure.

But in November, he and his fellow citizens of Solano County will have to vote on preserving their backyard as is or opening it up to others.

For the "PBS NewsHour," Paul Solman.