THEATER : Fantasy at the Fringe : Cornerstone Theatre chose to present its futuristic ‘Rushing Waters’ in Pacoima because, they say, the margins of L.A. are the city in microcosm.

In 1986, when Cornerstone Theatre Company began its vagabonding adventure from small town to small town across the country, no one associated with the group ever imagined that it would end up in Pacoima, staging a futurist musical fantasy set on the one remaining plot of land after the Big One has hit Los Angeles.

Then again, the whole nature of Cornerstone is that it is never absolutely certain where it is going next. Only that it is going on.

But with its new show, Migdalia Cruz’s “Rushing Waters,” opening Thursday at the Boys & Girls Club of the San Fernando Valley, Cornerstone is also going out on a limb as it never has.

It has never produced a show from the ground up in a large, multiracial urban neighborhood like Pacoima. (“The Toy Truck,” the company’s first of several planned productions during its extensive L.A. residency, was done at Angelus Plaza, a compact downtown retirement community).

It has never produced a completely original play with a playwright outside the company. It has never produced with a cast and crew in which new visiting artists outnumber longtime resident artists. It has never produced a musical with a new score (by Danny Vicente, Darren Brady and LaRue Marshall) supported by a live band (Vicente and Brady).

And as for the futurist musical fantasy business? Well, Cornerstone has never done that before, either.

Bill Rauch, Cornerstone’s co-artistic director and the play’s director, is asked if people were a bit fearful about the project.

“Not fearful, really,” he says, “but curious about how things would turn out.”

This isn’t smooth talk to cover sheer terror. It’s a kind of guiding principle behind the company, which has consistently defied expectations by adapting the classics to be set in the community Cornerstone visits.

In the mid-’80s, young artists like Rauch and Cornerstone co-founder Alison Carey were supposed to go from well-endowed college careers at Harvard into the big, established theaters--not hit the road, settle down in a strange town and persuade locals to join them and put on a show.

But the road called.

“We knew early on that if we had success, it wasn’t necessarily what we wanted to have,” says Rauch, 30. “And it wasn’t a case of reacting against a certain kind of production form, but the general theater audience, which is so narrow and not reflective of the larger community. We knew that we couldn’t grow as artists playing to that same audience all the time and that whole communities were being left out.”

“To my mind, Cornerstone is on the forefront of cultural democracy,” says director and Los Angeles Festival head Peter Sellars. “We always hear from artists telling us what America is about, but we’ve seldom seen artists such as these who go out and meet America. They have none of the change-the-world arrogance. They’re not good at promoting themselves. They just go out and do it.”

The continuing challenge, those close to Cornerstone say, is dealing with the very different Americas within the nation. Pacoima, Rauch acknowledges, may be very different from Norcatur, Kan. (where Cornerstone staged its 1988 Moliere adaptation, “Tartoof” and where its rural headquarters remains), but both towns share a reality that attracts the ensemble group like a magnet: marginality.

Pacoima, struggling with many of the same tensions that plague South-Central--gangs, drugs, poverty and crime--is miles and miles from the inner city, but the company views it as Los Angeles in microcosm.

“While we’re in L.A.,” Rauch says, “we’re going to the fringes, the forgotten places of the city, and Pacoima exemplifies that.”

One would expect, then, that the author of “Rushing Waters” would be a Pacoima native. Instead, Cruz--whom everyone at rehearsals at the Boys & Girls Club calls “Micki”--has risen from the tough streets of the South Bronx to prominence among experimental Latina playwrights. Rauch and she first worked together on “Occasional Grace,” a collaborative work by New York’s En Garde Arts company in 1991, and since then have wanted to join forces again.

Because of Cruz’s Puerto Rican background, Rauch says, “we knew a few eyebrows might be raised since she isn’t, say, Mexican-American, but Micki’s commitment to community is very akin to ours, and she also had experience with musicals,” such as her epic work with Hilary Blecher, “Frida.”

During her first visit to Pacoima in August and September, Cruz soaked up the lore and the people, from coffee shops to the library, where she learned about the local 1938 flood that killed several Japanese-American families.

Here was a trigger for her story, set in both a post-earthquake Hansen Dam refuge for abused children and a waiting room for the spirits of famous adults with some historical connection to Pacoima (from the first black postmaster, Nancy Avery, to singer Ritchie Valens). Into their midst arrive a feuding mother, father and daughter (played by Maggie Palomo, Benajah Cobb and Trinidad Barajas).

During the months of writing, rewriting and rehearsals, themes galore began to emerge. The play’s apocalyptic dimension intrigued Cruz, while Rauch began to see the play’s Pacoima as a kind of Noah’s Ark for America.

Cruz also saw how the lost souls that make up many of the musical’s 41 roles organically linked with her sense of Pacoima as “a sad, forgotten place, but with a generosity of spirit.”

But the idea that seems to stir Cruz the most--the well-being and future of children--became harsh reality for the company Jan. 9, when 12-year-old Tiffany Dozier was killed by a stray bullet outside the club after coming from a party there.

Afterward, Cruz says, “the company met, and one member was concerned about continuing to work here, but I felt that this was absolutely why we needed to stay. I wasn’t shocked, because I grew up knowing to always check your backside. But I understood the fear.” She immediately dedicated “Rushing Waters” to Tiffany and Efrain Lopez, a Pacoima man shot by police after waving a broom in the air.

The group agreed with Cruz, and day after day of rehearsals in the club’s multipurpose room is filled not with mourning, but with a nervous, expectant energy as opening night approaches.

At the first run-through of the show involving every element--from the band to designer Lynn Jeffries’ shifting set on wheels--Cruz sits quietly in the rear, while Rauch patiently takes the mostly non-professional, local actors through their paces.

Rauch’s calm approach, especially toward the nearly dozen children in the cast, often pays off. For instance, young Octavio Ramirez reminds Rauch where Trinidad should be positioned at the opening of an important scene. “That’s good,” Rauch says in an aside, “everyone’s thinking.”

During breaks, Jackie De Santiago and Harris Craig Jr., both 17 and both with high school performing experience, continue working as guides for the children.

“I’m Amiocap, that’s Pacoima spelled backward, you know,” says Craig.

“And I’m Mocapia, because she’s kind of mixed up,” Santiago says. Cruz, who found herself something of an oddity as a Puerto Rican in a town with a long Mexican-American heritage, made Mocapia part Puerto Rican, which gets her in trouble with the local Pacoima girls.

“The first draft was soooo sad,” Santiago says, “but it’s become a little more hopeful since then.” Craig adds, “And it’s brought a lot of people together who probably wouldn’t have ever talked to each other.”

Craig might not realize it, but he just expressed the ideal of this most idealistic of theater companies.

Where and When What: “Rushing Waters.” Where: Boys & Girls Club of the San Fernando Valley, 11251 Glenoaks Blvd., Pacoima. When: 8 p.m. Thursdays through Saturdays; 5 p.m. Sundays. Opens Thursday, through Feb. 28. Price: Pay what you can; $7 is suggested. Call: (818) 890-7304.