State officials said construction delays and redesign costs could use up the Highway 520 bridge's $100 million in reserves.
Most of the costs are related to design errors by the Washington State Department of Transportation that caused cracks in the first four giant pontoons. These required repairs, while others have been redesigned.
The state estimates it may have to spend another $128 million for the repairs.
Information released Friday on the WDOT website comes a month after new Transportation Secretary Lynn Peterson and 520 program administrator Julie Meredith held a news conference to reassure the public that the bridge project's $250 million reserve fund is sound.
The state doesn't have concrete plans for finding more money if the project requires it.
Crews would have to inject epoxy into the cracks and have welders install steel cables to squeeze the pontoons tight. The repairs would then get covered with a carbon fiber wrap.
The construction delays will push back the opening of the new floating section from late 2014 to 2016.