A Concept That’s (Intentionally) All Wet : Dance: Choreographer Heidi Duckler is floating another new idea. This time her troupe will perform in the L.A. River.

Dancer-choreographer Heidi Duckler wades through the stale-smelling water, over the incandescent green algae, past the ruins of a concrete train trestle to the center of the Los Angeles River.

It is a profoundly urban setting. Sloping concrete barriers hold the river in check, electric transformers buzz overhead and the nearby Golden State Freeway crawls toward the horizon. In the middle of the river, two androgynous dancers bounce on the frames of rollout beds--props that easily could be debris from upstream.

It is not a place where it seems natural to dance.

But then, neither was the Laundromat. Or the gas station. Or the library. That didn’t stop Duckler. Over the last seven years, Duckler and her troupe, Collage Dance Theatre, have danced in all those places and gained a reputation for making locations as integral to their performances as music and movement.

“When I started, I used lots of props,” Duckler says. “I filled the stage with ladders, hair driers, wading pools. . . . There became so much stuff that I began to wonder: Why bring all the stuff into the theater? Why not go to the stuff?”

That evolution has brought Duckler to “Mother Ditch,” a multimedia performance Saturday night in Atwater Village that she directed, produced and choreographed. The title is a translation of the Gabrielino Indian name for the river, Zanja Madre. Duckler first chose this stretch of now-paved river, at Glendale Boulevard, unaware that it was the site of the Gabrielino settlement Yang-Na, which predates Los Angeles by centuries.

Now, Duckler is up to mid-boot in the Mother Ditch, careful of every step on the algae-covered bottom. The dancers, too, are having a hard time moving with grace in rubber boots and quick-moving water. Making the rehearsal even more tedious is the fact that dancers Elizabeth Nairn and Eli Nelson can’t hear Duckler’s commands over the rushing water unless she wades out 100 feet from the bank.

The dance duet is the centerpiece of a 45-minute performance that is a tremendous logistic feat. First, Gabrielino elders will bless the performance. Then, while the dancers perform, a 16-person choir will sing words drawn from Joseph Conrad’s “Heart of Darkness.” They will be accompanied by eight accordions and the revving engines of 20 motorcycles.

In addition to all this, artist B.J. Krivanek designed 50 slides to be projected onto the concrete bridge ruins, overlaying each segment with themes about nature, immigration, culture and individualism. Finally, a solo violinist is supposed to float obliviously past the dancers, fiddling through the chaos.

“And the first time it will come together will be at the tech rehearsal on Friday, the day before the performance,” Krivanek says.

Amazingly, this “Mother Ditch” is a scaled-down version of what Duckler originally intended. In 1993, she got a grant from the organization Dancing in the Streets to research a piece set in the Los Angeles River. Her vision included multiple performances and art and dance workshops in the community. But the $3,000-grant she got from the city Department of Cultural Affairs was one-tenth of what she needed for those grand plans.

Not unlike creating visual art with found objects, Duckler created her show with found talent. Once she decided to use Atwater Village, she walked up and down Glendale Boulevard, talking to shop owners and residents. When she found something interesting--like a photo of the Flaming Knights Harley-Davidson motorcycle club--she considered whether it might fit into “Mother Ditch.” The choir is composed entirely of Atwater Village residents; the accordionists all take lessons at a nearby accordion shop.

She did the same thing with the actual location--using the old bridge supports for the projections and the concrete slopes of the channel for graded seating. Likewise, the theme of “Mother Ditch”--the polarization of urban reality and pastoral nostalgia--emerged from the setting.

“Rather than transform the space, the idea is to organically develop within the space,” Duckler says. That’s the difference between site-specific work and outdoor performance.

This is the sixth installment in Duckler’s “Urban Extinction” series, which focuses on community gathering spots that are endangered by Americans’ changing lifestyles. The first, in 1988, was “Laundromatinee” at the Thrifty Wash in Santa Monica. Modern apartment buildings, with their little laundry rooms, will eventually eliminate communal clothes-washing, Duckler explains. She explored the potentially similar fate of gas-and-service stations in “Parts and Labor” and of libraries with “Out of Circulation.”

“Mother Ditch” varies from its predecessors in that the river isn’t disappearing because of a change in lifestyle. It isn’t facing extinction, Duckler says, it’s already invisible. “No one knows there’s a river here--this concrete snake that winds through the city , “ she says. “At one time it was a very important river, and supplied us with water. Now it’s just a drainage ditch.”

Once she recovers from “Mother Ditch,” Duckler says she might try a guerrilla piece--something in an electronics store where dancers emerge from refrigerators and appear on all the TVs. Managers at Circuit City haven’t exactly embraced the idea.

While she’s glad her work is unique, Duckler expresses some surprise that few other people do site-oriented performances in Los Angeles. The weather is good. There’s an audience for almost anything. There’s local talent everywhere you turn.

“I can see why, though,” Duckler says after her three-hour rehearsal in 90-degree heat is done. “It’s grueling.”

* “Mother Ditch” will be performed at 7:30 Saturday under the Glendale Boulevard bridge in Atwater Village. The entrance to the riverbed is off Ferncroft Road. Tickets are $10. Call (818) 788-5113.