This other Eden, demi-paradise, this precious stone set in the silver sea, this earth, this realm, this Los Angeles.

—Steve Martin (and Shakespeare), L.A. Story

The entire world seems to be rooting for Los Angeles to slide into the Pacific or be swallowed by the San Andreas Fault.

—Mike Davis, Ecology of Fear

Experience the beauty… of another culture while learning more about wastewater treatment and reuse.

—Brochure for the combination water reclamation plant and Japanese garden in the San Fernando Valley

PROLOGUE: FROM WALDEN TO L.A.

There are many places in L.A. you can go to think about the city, and my own favorite has become the Los Angeles River, which looks like an outsize concrete sewer and is most famous for being forgotten. The L.A. River flows fifty-one miles through the heart of L.A. County. It is enjoying herculean efforts to revitalize it, and yet commuters who have driven over it five days a week for ten years cannot tell you where it is. Along the river, the midpoint lies roughly at the confluence with the Arroyo Seco, near Dodger Stadium downtown. L.A. was founded near here in 1781: this area offers the most reliable aboveground supply of freshwater in the L.A. basin. It’s a miserable spot now, a trash-strewn wasteland of empty lots, steel fences, and railroad tracks beneath a tangle of freeway overpasses: it looks like a Blade Runner set that a crew disassembled and then put back together wrong. It’s not the most scenic spot to visit the river but may be the finest place on the river to think about L.A.

Like so many writers who come to Los Angeles—and I moved here seven years ago—I have succumbed inevitably to the siren call to write about the city. The long-established procedure has been to explore why one loves it or hates it, or both, and to proclaim loudly in the process that L.A. is the American dream or the American nightmare. The tradition tempts writers with a combination of navel-gazing and arm-waving that proves impossible to resist for too long.

Of course, I am a nature writer—a unique brand of writer that has felt no compulsion whatsoever to write about L.A. and even less to live here. Though you could toss an apple core into the bushes in Missoula, Montana, and hit a nature writer, I have found four practitioners so far among the ten million people in L.A. County, and one, my friend Bill Fox, fled to Portland for a couple of years. “Is there nature in...