WASHINGTON — The San Joaquin River is now in very select company.

Few waterways get a second chance like this. Those that do form an impressive roster: Chesapeake Bay, the Everglades, the Potomac. Direct comparisons are dangerous, but the restoration campaign undeniably puts the San Joaquin River on the national map.

“It’s being talked about as one of the biggest restoration efforts for a river system,” said Dave Koehler, executive director of the San Joaquin River Parkway and Conservation Trust.

In some ways, the San Joaquin River restoration is incomparable. Salmon restoration has never been tried in rivers this far south in the United States. No other river this long is dry for 60 miles in the middle of its run to the ocean.

Besides, no two cleanups are the same.

The Potomac River, for instance, once presented serious problems. The badly polluted, 330-mile river benefited from more than $1.1 billion worth of upgraded waste-treatment plants starting in the 1970s. Conditions improved; fish populations increased and troublesome algae blooms decreased.

Screening out pollutants, though, is very different from returning water and fish to a dry channel.

Since 1999, when the relatively small Edwards Dam was removed from Maine’s Kennebec River, the advocacy group American Rivers says “more than 600 outdated dams have been removed” from rivers nationwide.

No dams are coming down on the San Joaquin, but scientists and water experts interviewed by The Bee say they don’t know of any previous effort in the country to restore a salmon population that’s been missing for so long and on a river that’s so big. The San Joaquin River’s salmon disappeared some 60 years ago, with construction of Friant Dam.

“I can’t think of another river that’s coming so far from a lost and degraded condition,” said Monty Schmidt, senior scientist with the Natural Resources Defense Council. “It surely is one of the biggest river restoration projects around.”

San Joaquin River restoration is expected to cost somewhere between $600 million and $1.2 billion, by initial estimates. Farmers assume it will cost more and environmentalists assume it will cost less. The final price tag will depend in part on the solutions selected for certain reaches — or sections — of the river.

Fixing Florida’s Everglades, by contrast, will require at least $10.9 billion over the next 30 years. State, local and federal sources will share the cost, as they will with the San Joaquin River restoration. The nonpartisan Congressional Research Service called the Everglades project authorized by Congress in 2000 the “largest investment in ecosystem restoration” ever approved on Capitol Hill.

But there are even larger price tags elsewhere.

Cleaning up the Great Lakes has an estimated cost of $20 billion, while Chesapeake Bay cleanup will take at least $15 billion. The Congressional Research Service noted, though, there are big differences in federal roles, responsibilities and goals among the projects.

With costs so high, it’s crucial to figure out what works and what doesn’t. Unfortunately, accurate assessments take a long time because problems decades in the making can take decades to fix.

Since the mid-1990s, for instance, state and federal officials have lavished money and attention on the so-called Cal-Fed program, which is designed to restore health to the Sacramento-San Joaquin Delta. By 2030, upwards of $8.6 billion is supposed to be spent.

In the past year, the Cal-Fed program has paid for fish screens near Tracy, protections for the Suisun Marsh, and the purchase of water for fish and wildlife, among other efforts.

Reviews, though, are mixed.

“While Cal-Fed has had its successes,” California’s nonpartisan Legislative Analyst’s Office concluded last year, “there is common agreement … that the ‘business as usual’ Cal-Fed is not well-positioned to meet its objectives.”

Still other projects show how long restoration projects take, as well as the proliferation of superlatives.

The flow of the Elwha River in Washington state, for instance, is impeded by two dams that are slated for removal. The advocacy group American Rivers, on its Web site, still calls this $113 million dam-removal project “the most significant river restoration effort of our time.”

The 45-mile-long Elwha, though, is significantly shorter than the San Joaquin.

Sizewise, the 263-mile Klamath River, which threads through Northern California and Oregon, can compete. The river once supported the third-largest salmon run on the West Coast. Officials are studying plans that could lead to the removal of four Klamath River dams by 2020, at an estimated cost of $200 million.

The Klamath, though, never went dry, and its salmon runs didn’t go extinct.

And so, like the other rivers and waterways being restored now and in the future, it really can’t compare with the San Joaquin.