The King County Council has given its final approval to an agreement to build a new professional basketball and hockey arena in Seattle, and the City Council is expected to follow suit.

The votes Monday came despite a lawsuit threat from the Longshore union, which says the agreement violates state environmental law.

Hedge fund manager Chris Hansen is leading a group that wants to build the $490 million arena with $200 million in public financing. The public investment would be paid back with rent money and admissions taxes from the arena, and if that money falls short, Hansen would be responsible for making up the rest.

Hansen wants the stadium built near the Mariners and Seahawks stadiums, but the agreement calls for alternative sites to be reviewed as well.

The county council unanimously approved the deal. Some council members said it was crucial that the agreement doesn't require new general taxes, and that an environmental review will be undertaken.