In Newark’s case, repairing the damage will not be easy. Mr. Rich, the planning director, led the way on foot the other morning from the train station to the new boardwalk. The trip required crisscrossing streets with meager accommodation for pedestrians, clambering up the exit ramp of an old bridge and hugging the gutter of a four-lane boulevard that lacks traffic lights allowing people to cross into the park. Along the way, he pointed out a riverside brownfield, the former Market Street Gas Works, now a cleanup project for PSE&G, the utility company. Next door, a grim mirrored-glass office building, headquarters for New Jersey Transit and Horizon Blue Cross Blue Shield, squatted atop a multistory garage.

It’s hard to envision how Riverfront Park will get around those obstacles.

And then there is the river. A state court ruled two years ago that Occidental Chemical Corporation, the successor to Diamond Shamrock, was principally liable for the costs (from $1 billion to $4 billion) of cleaning up the Passaic, but the company has contested the ruling. The next phase of Riverfront Park, to be completed in the spring, envisions the boardwalk stretching toward Penn Station. Restoring parts of the riverfront in the ethnic and racial mix of northern neighborhoods, for equity’s sake, will present a whole fresh set of hurdles.

Still, what has been built so far goes a long way. If a single downtown building like the Blue Cross Blue Shield headquarters separates the city from its river, a modest stretch of boardwalk knits them back together. At a ball field across the boulevard from the new park, Marcelino Arce, a youth baseball coach, described how some children in the Ironbound neighborhood had no idea the river was even there. Now, they must dodge traffic on the boulevard; but once across, he told me, it’s “a whole new world.”

That world includes a few zigzagging walking paths, with signs, by MTWTF, a graphic design firm, recounting the history of the river and its industries. There is an osprey rookery built into a copse of trees at an overlook onto the river. The city still needs to install those traffic lights and the park needs more seating.

As for the boardwalk, made of recycled plastic, its bright orange can summon up what Christo and Jeanne-Claude called “saffron” to describe the color of their “Gates” in Central Park. But police cones may leap to mind. Or Agent Orange. For his part, Mr. Weintraub said the orange was picked after eliminating various gang-related colors. Whatever. It is not ideal.

Newark deserves an elegant waterfront. That said, the orange boardwalk also acts like a giant highlighter, drawing attention to the park — as the project hopes to draw people from all over the city back to the Passaic, one patch of recuperated riverfront at a time.