“Properties of Thirst” by Marianne Wiggins is, first and foremost, a Great American Novel. But it’s also many other things — a love story, a war story, a paean to the West that doesn’t shy from its violent history, especially over who owns and profits off water, its most precious resource.

“California has been looked upon as the promised land, but without water, you may as well be on the moon,” said Wiggins, who lives in Venice (Los Angeles County) with her daughter, photographer Lara Porzak. “It’s a continual subject for us as a species, and now that we are going to space, what are we looking for? Water, because we require it as humans.”

Any tale about California and water, of course, evokes the 1974 film “Chinatown,” starring Jack Nicholson and Faye Dunaway. But even as the book salts the plot with wonderful, unsentimental depictions of movie stars, its real interest is in another American archetype: the outsider.

Set after the bombing of Pearl Harbor, it tells the story of the Rhodes family, California ranchers who have long fought a losing war against Los Angeles’ watermen, and the idealistic Department of Interior lawyer Schiff, a Jewish American who is tasked with overseeing Manzanar, the Japanese internment camp, next to the Rhodes’ ranch.

Behind the novel is an equally powerful story. Wiggins, a finalist for the Pulitzer Prize, was almost finished with the manuscript for “Properties of Thirst” when she suffered a stroke in 2016 that left her unable to write, with no memory of the book. Over the next several years, her daughter helped her finish it.

“Mom’s voice is impossible to imitate — I didn’t even try,” Porzak said.

She read her mother the book aloud dozens of times (“This is really good!” Porzak would say) and then, through the painstaking work of combing through her mother’s journals and notes, they began to rebuild the final chapters.

But even when Wiggins immersed herself back in the narrative, “the book did not feel like a part of myself,” she admitted. “I felt like I was attempting almost what a biographer feels to inhabit a previous, nonliving voice.”

“We just tried to do it word by word,” added Porzak. “I would type it out, then Mom would move things around. If I wrote a really bad sentence, that would get Mom riled up; she had to fix it. So that was a productive way to get it done.”

In many ways, Porzak had been involved in the novel from the start. On a road trip with her mother back from Death Valley in the early 2000s, they passed by Manzanar and decided to stop.

“I grew up in Lancaster County, Pa., and I had no idea that we as a country did this to our own citizens, that we incarcerated our own Japanese Americans,” Wiggins said. “We didn’t incarcerate our German citizens. It shocked me. Thank goodness we had the wisdom to set aside this place and keep it intact. To share the truth of it.”

She knew right then that she had to write about it in a book, but that she couldn’t use a perspective from inside the camp. “I couldn’t appropriate that history,” she said. “So I had to find another way in. That was Schiff.”

What makes the novel powerful is its ability to show what the grinding day-to-day of a terrible injustice looks like. How many cans of tomatoes does it take to feed 10,000 people? How many barbers and schoolteachers and doctors does the camp need? These questions fall to Schiff, who tries to do good within a structure that is inherently wrong.

While Wiggins grew up on the East Coast and lived for many years in London, the book’s sense of place is distinctly Californian.

The first time she visited, in the mid-’80s for a book tour, “California hit me hard,” Wiggins recalled. “I came from England, and so the horizon is quite remarkable — it’s an American horizon.”

In its sweep and ambition, the novel often feels like a film epic, and while it has moments of joy, there’s no Hollywood ending.

“The dividing line between popular fiction and literature is that we don’t get happy endings as human beings,” Wiggins said. “Some people do, but there’s a balance between the tragedy and (the joy). With popular fiction, it’s always a happy ending — that’s why it’s so popular. Literature tries to hold a realistic mirror to life as humans live it.”

Properties of Thirst

By Marianne Wiggins

(Simon & Schuster; 544 pages; $27)