WASHINGTON » It’s been 14 months since a massive tsunami swept over parts of Japan, but federal officials still lack a comprehensive plan for detecting and disposing of the resulting debris that is expected to make landfall on the West Coast by sometime next year, a Senate panel was told Thursday.

David Kennedy, an assistant administrator with the National Oceanic and Atmospheric Administration, or NOAA, said his agency cannot definitively say when or how much of the floating debris will hit U.S. shores.

That’s largely because the March 2011 tsunami unleashed an unprecedented debris field, estimated by Japa­nese officials at 5 million tons. They guess 70 percent of it sank immediately, leaving the rest to drift on a 2 1⁄2-year journey toward the U.S. mainland.

Computer modeling by scientists at the University of Hawaii shows the debris is halfway across the Pacific Ocean. But the garbage is so dispersed that it long ago stopped showing up on satellite images. Instead, NOAA is relying on classified, high-resolution satellite images and debris sightings by ships and boats.

Kennedy was grilled for an hour at the subcommittee hearing by Sens. Maria Cantwell, D-Wash., Mark Begich, D-Alaska, and Olympia Snowe, R-Maine, members of the Senate Committee on Commerce, Science and Transportation. It was the Senate’s first oversight hearing on the tsunami debris plan.

Cantwell has called on federal authorities to develop a plan to assess the debris and prepare for any threat it could cause to coastal communities and their economies.

Already in Alaska, soccer balls, Styrofoam and even a squid boat have arrived from Japan, and a rusting motorcycle with Japa­nese license plates was found last month in a large metal container on a British Columbia beach.

Earlier this month, two dozen floats believed to be from Japan washed into the Strait of Juan de Fuca.

When Begich asked about NOAA’s debris cleanup plan, Kennedy said, "We don’t have the authority to mount a cleanup."

Instead, states would be mainly in charge of removing the debris, he said. But other agencies would have roles, too. The Coast Guard, for instance, would sink any "ghost ships." Hazardous materials will have to be disposed of separately.

Cantwell at times pressed Kennedy for detailed answers he did not have. Kennedy did not directly respond to her question on what 911 operators ought to tell callers reporting tsunami debris. When she asked about the possible effect on migratory fish such as tuna and salmon, Kennedy said he would have to defer to NOAA’s fisheries experts.

At one point an exasperated Cantwell summarized Kennedy’s testimony as, "We don’t have a clue about the debris."

Kennedy assured her that NOAA was doing its best to blunt the economic, ecological and navigational problems that could follow in the debris’ wake. He was clear, however, on one point: NOAA does not have enough money for the task.

Washington and Hawaii have begun coordinated contingency planning with state and local agencies and organizations; Alaska, Oregon and California have not.

Experts expect the tsunami flotsam to wash up on Washington’s coasts for years. According to the projected 15-year debris path by the University of Hawaii, the main current will join the North Pacific Garbage Patch between Hawaii and California around 2015, swirling clockwise through ocean gyres for years.