A bill approving a new Interstate 5 bridge over the Columbia River would authorize $450 million in bonds to pay for Oregon's share, but it doesn't say how the state would pay off the debt over the coming decades.

State lawmakers heard public testimony on the topic on Monday.

Paying down the bridge debt would cost roughly $30 million per year.

In the short term, the state can use unanticipated federal transportation dollars to cover the debt. But after that money runs out in two to three years, the state would have to approve a new revenue source, such as a gas tax or vehicle fees. Otherwise, the state would have less money available for other transportation projects.