The Oscar B ferry makes a test run in February. The ferry has been out of service since mid-December.

CATHLAMET — The Oscar B ferry between Westport and Puget Island has been out of service since mid-December from debris clogging the cooling system.

There is no timetable for how long the ferry will be shut down. It is the last ferry on the Lower Columbia River and the only way for vehicles to cross the river besides the Astoria Bridge and the Lewis and Clark Bridge in Longview.

Wahkiakum County Public Works Director Chuck Beyer said he hoped to have a repair plan submitted last week to the U.S. Coast Guard, which officially shut down the ferry.

Once the Coast Guard signs off on the work, it will still take a few weeks for materials to ship and the repair work to be done, Beyer said.

The clogged cooling line causes the generator to overheat. Without the generator, the ferry’s hydraulics and steering won’t work.

Beyer said debris from recent storms are partly to blame, although the clogging seems to be caused by a design flaw.

“There had been issues in the past with the intakes getting clogged, and material getting into the filters,” Beyer said.

There is no cost estimate yet for the repair. The $5.7 million ferry, which went into service in January, is still under warranty.

The Oscar B remains docked in Puget Island.