The dry gulch has many faces.

Commuters weave down it on the West's oldest freeway. Top engineers converge in its dusty draw to mount America's exploration of space. And on New Year's Day, millions of television viewers enviously admire its stadium, washed in the warm winter sunlight.

It passes the Rose Bowl and the Jet Propulsion Laboratory and goes under at least seven historic bridges before emptying into the Los Angeles River. Seeking to build the arroyo's image as a watershed is a coalition of planners, environmentalists and political leaders. They are wrapping up a half-million-dollar study of ways to tie together natural areas in the drainage, give the river its meander back, and "daylight" lost tributaries now buried in storm drains.

To create the impression of the arroyo as a public green space, planners are also working with Caltrans to shut down the Pasadena Freeway for a Sunday next year so people can amble and ride bikes down what was originally meant to be, in its true sense, a parkway.

"When you think of a river as a whole, it gives some kind of coherence to that little park down the street," said Robert Gottlieb, professor of urban and environmental policy at Occidental College, who is planning the event. "If there's anything that connects the corridor today, it's the freeway."

Despite the traffic careening down its southern reach, the arroyo fits ideally into a growing strategy of restoring and creating urban open space, Gottlieb said. It connects the mountains to the Los Angeles River 21 miles away. It traverses white, black, Latino and Asian neighborhoods, streets lined with old hotels, lofty mansions and teetering bungalows. And it is flanked by enough public land that expensive property acquisition would not be a major issue.

"The arroyo captures the county's demographics and it has a lot of potentially rich ecological reservoirs to play with," Gottlieb said.

The study--called the Arroyo Seco Watershed Restoration Feasibility Study--brought together numerous scientists, engineers and consultants, as well as agencies including the Santa Monica Mountains Conservancy, the Los Angeles County Department of Public Works and the National Park Service. Ideas ranged from the everyday--new parks and bike trails--to what critics might call delusional--say, fishing for steelhead trout in Pasadena.

The public relations campaign for the arroyo is not nearly as quixotic, though, as the quest to convince people that the Los Angeles River is worth fixing up. That stream, which has attracted almost $100 million in state funds for its restoration, is lined in concrete almost from head to toe, ratcheted down by a rust belt of industry from downtown to Long Beach.

By comparison, the arroyo water trickles, and occasionally roars, through a lost era. Already some parts have been restored. In Pasadena, horses clop through sand and brush, past prickly pear cactus and rocky ravines. Joggers move between scenes of the city's oaken, soft-lit gentility and the raw dirt of a desert wash.

"Is the arroyo going to be a hard sell?" asked Lynne Dwyer, executive director of Northeast Trees, which is leading the study with the Arroyo Seco Foundation. "No, it's like mom and apple pie. Creeks and the Arroyo Seco."

The most ambitious element of the study--and always the most controversial idea when it comes to river restoration--is a look at possibly ripping out the concrete banks and recreating a natural meander to the watercourse.

"One of the things that makes it more feasible here is you don't have development right up to the arroyo like you do on the L.A. River," said Terri Grant, assistant head for the watershed division of the county Public Works Department.

Engineers at Montgomery, Watson & Harza estimated that it would cost $500 million to buttress bridges and buildings, and construct earthier, tree-lined banks to contain flood waters. Instead of rushing down the constant slope of the channel, the water would drop off small steps into ponds and twist in braids through a much wider stream bed, slowing its descent.

Although you might not know it in Los Angeles, flowing water naturally does not move along a path as straight as the Harbor Freeway, but bends and pools and twists. It branches and merges and doubles back on itself like, well, a river.

The two main parts of the arroyo under consideration for being let loose from the channel would be in Pasadena: a stretch through the Brookside Golf Course north of the Rose Bowl, and another south of the Colorado Street bridge. Other parts closer to Los Angeles would keep the banks and lose the concrete floor.

"The idea is to create a natural stream system, which requires a lot more space than is currently taken up by the trapezoidal, concrete-lined channel," said Chip Paulson, an engineer at Montgomery, Watson & Harza.

'I Think They're Insane'

Critics call the plan pie in the sky. Officials at the Rose Bowl Operating Co., which manages much of Pasadena's section of the arroyo, including the golf course, vehemently disapprove.

"I think they're insane," said Porfirio Frausto, president of the board for the company. "They're talking about naturalizing a flood control channel. Well, why do you think it is a flood control channel?"

The county and federal governments began constructing the region's channels in the 1930s to stop deluges that periodically devastated the basin and valleys.

Frausto said the stream would eat into the golf course's terrain and periodically flood the greens, depositing silt and flotsam while shutting down an economic engine for the city. Frausto said the 36-hole course brings $3.5 million to Pasadena annually and provides parking space for the Rose Bowl.

"They say, 'Don't you want to see salmon in the Arroyo Seco?' " he said. "Well, I want to see myself fly too. . . . They're nice people, but we'll fight this tooth and nail."

Los Angeles River advocates met similar opposition, and have largely shifted their focus to less rancorous proposals.

Another, perhaps less dramatic, part of the Arroyo Seco study suggests that a hidden network of waterways that used to feed into the arroyo can be unearthed.

"Where did all these ancient creeks go?" Dwyer said. "Well, now they're storm drains. Are they in people's backyards or can some of them resurface?"

Looking over county maps, she and her Northeast Trees colleagues determined places where the underground pipes could be dug up to create natural-looking creeks twisting their way to the main arroyo. Rainbow Canyon, a small tributary coming off Mt. Washington, is a prime candidate because the drain pipe runs under an existing nature park.

"As it is, the water is still running through a watershed, but once it hits a pipe, it's not doing any good," she said.

Yet even in its ambiguous state, the watershed supports a wide variety of life, especially in the upper reaches.

To study the fish there, biologist Matt Stoeckler climbed into a shadowy bowl of the Angeles National Forest near the arroyo's headwaters a few miles above Pasadena. Deep in a remote gorge, the loose rock slopes are so steep that the trail has to leave the river bottom and skirt along a ridge to the east. Stoeckler stumbled upon bears and found pools as deep as 15 feet, supporting healthy populations of rainbow trout.

"If you see fish 7 or 8 inches long, with a crimson side, that's definitely a rainbow," he said.

After his trek and a swim, Stoeckler considered how to improve the habitat for the rainbow, as well as how to bring migrating steelhead trout back up from the ocean and allow native species to thrive.

The key element relies on the same old controversy, however: restoring a natural meander. The water simply moves too fast in the straight channels for the fish to swim upstream.

"If the system is deconstructed and naturalized, the fish will come back," Stoeckler said.

For less controversial improvements for the fish, he suggested that Pasadena install netting at the Devil's Gate Dam where the stream water is diverted into the drinking water system. "It's got to be screened so it is not sucking in these rainbow trout," he said.

Seeking to Link Wildlife 'Islands'

Of course, fish are not the only wildlife that use the arroyo. Biologists mapped out bits of open space from La Canada Flintridge to Mt. Washington, looking for links that would allow wildlife to wander between these "islands" and maintain healthy populations.

As it is, bobcats have been sighted as far south as South Pasadena, though deer will not go as far, and mountain lions and bears stay in the mountains.

"It doesn't call out to us right now to build a corridor for mountain lions from the Santa Monicas to the San Gabriels," said Verna Jigour, a conservation ecologist who prepared that part of the report. But, she added, bobcats and foxes might move between the ranges.

In the end, the study presumes to answer the question that haunts Los Angeles' urban park movement: Can we all get along?

Yes, equestrians, mountain bikers, bears, homeowners, commuters, soccer players, nature lovers and rainbow trout can live peacefully with flood waters, freeway overpasses, stadiums and rocket laboratories--all in one dry old gulch.

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Improving the Arroyo Seco

A coalition of environmentalists and government agencies is wrapping up a study that looks at ways to improve ecological habitat and recreational opportunities in the 46.6-square-mile Arroyo Seco watershed.