Nobody misheard Mayor Mike McGinn's battle cry when he was running for mayor: He would block the deep-bore tunnel under downtown Seattle, a bad transportation plan and a boondoggle. That stance softened in his later campaign days; but even then, McGinn insisted that he would protect Seattle citizens from having to pay for cost overruns, which are nearly inevitable on projects like this.

Now the city (pitching in $930 million) and the county and state (covering the rest of the $4.2 billion tab) are proceeding under an agreement that, as of this moment, still saddles Seattle with any cost overruns (with no way to know how many millions that may be). People can live with the tunnel—McGinn included—provided that Seattle doesn't get stuck with more than its share of the bill. But state lawmakers passed legislation last year that says any costs in excess of the state's obligation "shall be borne by property owners in the Seattle area." Speculation abounds that the provision is unenforceable. But that is speculation. And for now, it is still the law.

"The legislature has made it clear they want the city to pay for cost overruns," McGinn says. He has repeatedly vowed to erase that liability before we pass "the point of no return," the point at which Seattle is committed to the tunnel and the law putting Seattle on the hook for cost overruns remains in place.

But McGinn has a problem. "I don't know exactly where the point of no return is right now," he says. Moreover, McGinn doesn't seem to have a plan to identify this point of no return or pull the emergency brake before we careen past it.

It gets worse. A phalanx of lawmakers in Olympia are already positioning themselves to replace the potentially unenforceable state law—which some say has no legal binding because "property owners in the Seattle area" is too ambiguously defined—with a law that is enforceable. On January 14, state senator Jim Kastama (D-25) introduced a bill clarifying that contracts for the tunnel builders cannot be signed until the City of Seattle provides a funding mechanism to pay for cost overruns. "Otherwise this could come back to affect the rest of Washington state," says Kastama, a member of the Senate Transportation Committee. He notes that Seattle and King County lawmakers were the ones who wanted a deep-bore tunnel (at 54 feet in diameter, the largest one ever proposed) and that a waterfront megaproject incurs the risk of overruns. For example, costs for the Big Dig on the Boston waterfront swelled from a $2.6 billion estimate to the $14.6 billion final tab. And King County's Brightwater sewage-treatment project is over budget and a year behind schedule; the tunnel-boring machines got stuck under Lake Forest Park last August and remain stalled. "If the city wants to proceed with an option that is inherently more risky, then the city should be responsible for those cost overruns," Kastama says. His bill has picked up six cosponsors.

Assuming the $1.96 billion earmarked specifically for the tunnel construction—the riskiest part of the $4.2 billion waterfront rebuild—was not enough and the project ran 50 percent over budget due to unpredicted obstacles, that would equate to a $1 billion bill. Seattle's 600,000 citizens, if they were on the hook, would need to pay $1,667 per person to settle the debt. A family of four would pay over $6,600.

But none of Seattle's legislative delegation has introduced a bill to unhook Seattle from the obligation. And the Seattle City Council, which signed a memorandum last fall agreeing to comply with the state law, isn't doing anything to protect Seattle, either. Does Council President Richard Conlin think we should pay for cost overruns? "No," he says. But is he doing anything to change that part of the agreement? No. He thinks the legislation will "die on its own."

"There is no practical reason to deal with it," Conlin says. "We need to get the project engineered and build it without cost overruns." He says that the point of no return would come when bids and estimates show the tunnel "can't make this budget."

"There is ambiguity," Conlin admits. "My feeling is that this is an ambiguity that we can live with until we have to deal with it."

Conlin may be correct that a court could toss out the provision at the eleventh hour—to the chagrin of the legislature—and pass the expense on to the state. But if he's wrong and Seattle must pay, as McGinn insists could happen, we could find ourselves years into a viaduct replacement project that's veering out of control and costing taxpayers big bucks.

If anyone can bring this issue to a head, it's the mayor who earned Seattle's vote by pledging to settle this dispute.

"He needs to decide how he is going to defend Seattle citizens from the state coming after their wallets," says Cary Moon, director of the People's Waterfront Coalition. "He's the lawyer and the mayor. He needs to figure out how to do this."

So far, McGinn proposes only asking state and city officials where they stand. "You can't solve an issue that people aren't even willing to talk about," he says. "My sense is that we should do something soon. The earlier we have that conversation the better."

But time is running out. The legislative session ends in March, the last chance to scrub the bad law this year. This fall, the Washington State Department of Transportation will issue a draft statement on the tunnel's environmental impacts; it will serve as a blueprint for proceeding with the project. And by next year, shortly after the final statement is issued, the contracts will be signed to begin digging under downtown.

If McGinn believes his own mantra about protecting Seattle taxpayers, he needs to get on it. Two ways McGinn can bring this issue to a head: (1) Ask for a legal interpretation of the Seattle cost-overrun provision from City Attorney Pete Holmes or state attorney general Rob McKenna. It may start a fire, but, again, it's better to know. (2) Organize Seattle's delegation in the legislature to introduce a bill that removes Seattle's obligation to pay for a state project.

"They should be operating with a clear and common understanding," says Moon. "Blithely believing there will be no cost overruns or that someone else will pick up the tab is not a very responsible or realistic way to make funding decisions."