PORTLAND — A breakaway chunk of rusty metal that plunged from the Memorial Bridge into the Piscataqua River between Maine and New Hampshire may have heightened concerns about the bridge, but it won’t change the timetable for action on the 80-year-old span, officials said today.

Bob Hassold, skipper of the Tug Alley Too, said he was leading four passengers on a tugboat cruise when he saw the 4-foot-long chunk plunge into the water just 50 feet ahead of his boat Monday.

“The bridge is falling apart,” said Hassold, whose tug passes under the bridge about 20 times a week. “They need to do something about it as quickly as possible. It’s in desperate shape.”

Maine and New Hampshire transportation officials insisted today that Memorial Bridge is safe, even though New Hampshire officials want to replace it as soon as possible.

No decision will be made until after both states receive a consultant’s report two weeks from now that considers options for Memorial Bridge, which connects Kittery and downtown Portsmouth, and Sarah Mildred Long Bridge, which includes a rail line serving Portsmouth Naval Shipyard.

New Hampshire contends both bridges must be replaced, but Maine hasn’t ruled out an option of building a single bridge to replace the two existing bridges, which are a half-mile apart.

Replacing both bridges would cost $200 million to $300 million, which would be shared by the two states and the federal government. Maine insists that careful scrutiny is necessary before spending so much money. Maine’s budget for all bridges – including 380 on a watch list – is only $60 million a year.

“These are 100-year decisions we’re looking at. So we’re going to have to live with the results of this for a long, long time,” said Maine Transportation Commissioner David Cole.

New Hampshire Transportation George Campbell said his state’s position is clear: Both bridges, which each serve more than 10,000 vehicles a day, are needed. But Campbell said the state is committed to having a fresh set of eyes in consultant HNTB Corp., which is considering options.

At present, HNTB has narrowed 60 different options down to five, including one that would eliminate Memorial Bridge and another that would replace it with a span limited to pedestrians and bicyclists. Three other options would replace Memorial Bridge and replace or repair Sarah Mildred Long Bridge.

The final report is due in two weeks. The timing gives New Hampshire little time to modify its request for U.S. Department of Transportation funding to deal with Memorial Bridge before an Aug. 23 deadline. A previous request for federal stimulus funding was rejected.

The two states do agree on one thing: It has become too costly to repair Memorial Bridge, which has deteriorated faster than expected and will need to be razed.

Last year, the weight limit for the bridge was reduced to 3 tons. While the bridge is safe for now, it will have to be closed in one to two years, said Carol Morris, spokeswoman for the “connection study” that’s being conducted by HNTB.

As for the chunk that fell, New Hampshire transportation officials are investigating.

Hassold said there’s no time for officials to drag their feet.

The falling debris was dangerously close, he said. “I could have been there a split second earlier and it could’ve fallen on the boat and killed some of the passengers,” he said.