Two state Senate committees this afternoon agreed to defer a bill that would extend the deadline for an environmental impact statement for Hawaii Superferry for a year.

The state Department of Transportation is confident that the environmental review, which is being performed by consultant Belt Collins, will be completed before the existing deadline in July.

But there are concerns that opponents of the project could file a legal challenge to halt ferry service if the review is not completed by the deadline. Under the law, Superferry is allowed to operate while the review is being conducted, but the law expires in mid-July.

The state Department of Transportation and the state Attorney General's office also believe that a one-year extension of the deadline would give state lawmakers and the public more time to analyze the environmental review.

The draft environmental impact statement has been completed and the public comment period is open until Monday. The state hopes to have the review finished in May and accepted before mid-July.

Mike Formby, the department's deputy director for harbors, said the state has only received about 25 public responses to the draft. Some of the project's opponents have discussed withholding comment until right before the comment period ends on Monday to make it more difficult for the state to complete the review on time. Other opponents have said they are boycotting the process because they question its legitimacy.

"We've read the blogs, we know that people are being encouraged to make last-minute submissions," Formby said.

The Senate Energy and Environment Committee and the Senate Transportation, International Affairs and Intergovernmental Affairs Committee deferred the bill. However, to make procedural deadline, the bill has been scheduled for a joint hearing before the two committees and the Senate Judiciary and Government Operations Committee.

The state Supreme Court, meanwhile, is reviewing a legal challenge alleging the Superferry law is unconstitutional.