RIVER OF ANGELS.(history and protection of the Los Angeles River)

It was a hazy May afternoon, and the poet Lewis MacAdams was trespassing as usual, in this case on the roof of the parking garage at the Los Angeles County Jail. The roof commands a view of the city's downtown, and MacAdams grinned and flung out his arm, as if to say, "Behold!" Below lay railroad tracks and power lines and barbed-wire fences that run in and out of a vast Union Pacific rail yard, a cluster of auto-salvage lots, and a concrete-crushing factory. In the midst of the prospect lay the object of MacAdams's devotion: the Los Angeles River.

The river is corseted in cement--poured in the nineteen-thirties by the Army Corps of Engineers to stop it from flooding--and further hemmed in by twelve crisscrossing freeways. Fenced off against would-be swimmers, its concrete banks tattooed with graffiti, referred to by local officials as a mere "flood-control channel," the river is nearly dry much of the year, and what water trickles through in high summer is mostly effluent from three sewage-treatment plants. The remainder of the dry-season flow is what one county official calls "urban slobber": storm-drain runoff carrying cigarette butts, pesticides, dog waste, Big Mac wrappers, and the occasional Yugo. Some carp and catfish manage to survive in the gunk, but they don't make good eating.

Because the river slinks along below ground level in many places, you have to climb and squint to actually see it. At the beginning of last season's pilot of "Boomtown," an NBC drama about Los Angeles, an elderly black man stands on a bridge and broods about the river. (Elderly black men serve the same role on television that crones serve in the Brothers Grimm.) "London's got the Thames, Paris's got the Seine, Vienna's got the Blue Danube," he says. "L.A.'s got a concrete drainage ditch."

Over the years, the river essentially vanished from the city's consciousness--while, courtesy of Hollywood, it remained vividly alive as a nameless and alien symbol of urban life. The moonscape that John Travolta drag-races along in "Grease"; the concrete trapezoid where Lee Marvin's contact in "Point Blank" gets shot and rolls down the culvert wall, dead; the geometric arroyo channels that Arnold Schwarzenegger and Edward Furlong weave their Harley through as they flee a cyborg in "Terminator 2"--that blank Corbusierian backdrop, that bulk of form without content, is the Los Angeles River.

Los Angeles is often described as a hundred suburbs in search of a city, and the river's fifty-one-mile course embodies that search. The river emerges from beneath the Sepulveda Dam, in the San Fernando Valley town of Canoga Park; moves east behind Warner Bros. and Universal Studios; turns south at Glendale and shoots through downtown Los Angeles, passing Dodger Stadium and City Hall; then widens as it falls through Maywood, Cudahy, and Compton, before reaching Long Beach, where it shrugs the trash of a hundred suburbs into the Pacific. In one of his poems about the river, Lewis MacAdams pictures it as a sort of twilit departure lounge to hell:

Through a tunnel grey with couches, And people sleeping in abandoned

automobiles, , the Arroyo meekly flows. . . ., Today there's, thirty guys with jackhammers, levelling, the river, ahead of an airport runway paving machine

MacAdams is fifty-nine. With a craggy, balding head and aquiline nose, and a willingness to be amused, he calls to mind a governor in ancient Rome. As a founder and the chairman of the board of Friends of the Los Angeles River, or FoLAR, he has for nearly twenty years fought to remove the concrete and restore a natural channel where steelhead trout can run upstream. "My goal is to get all the railroad tracks on this side of the river and put them underground," he told me, pointing east from the rooftop. "Then, eventually, we could have access to the river itself through parks all along the riverbank." MacAdams laughed and lowered his arm. He said, "If I were younger, I could definitely have a Robert Moses problem"--a reference to the builder who reshaped New York City by mapping out the Triborough Bridge, the United Nations, and numerous projects named after Robert Moses.

What one of MacAdams's environmentalist colleagues refers to as his "Aw, shucks, Ma'am, I'm just a poet" campaign has finally begun to take hold. In 2000, FoLAR and other environmental and civic groups sued to stop an industrial complex from being built on the Cornfield, a thirty-two-acre riverside parcel…