A dredging vessel is digging through heavy shoals that have choked ferry operations between Hatteras and Ocracoke for three weeks, and state officials say they might be forced to halt ferry service altogether for a few days or longer in February.

That’s when the dredge will be anchored in a clogged section of Hatteras Inlet where the channel is especially narrow and shallow. There might not be enough room for the ferries.

“It’s going to be a question of can the ferries safely navigate around that dredge as it’s working and dredging that channel,” said Harold Thomas, the state Ferry Division director.

Heavy shoaling – shifting deposits of sand that make navigation channels too shallow – has been a continual problem in Hatteras Inlet and Pamlico Sound since August 2011, when Hurricane Irene swept through the area. Three ferries have run aground since Dec. 21. Passengers and crews were stranded for as long as three and a half hours before they were able to get off the shoals.

“It just seems the whole channel system on the Outer Banks has been very different since Hurricane Irene,” said Roger Bullock, deputy operations chief for the Wilmington office of the U.S. Army Corps of Engineers, which is responsible for maintaining the channel.

“We’ve had to perform quite a bit more dredging. The ferry captains have never seen shoal patterns like this before,” Bullock said.

A dredge hired by the Army Corps of Engineers with state and federal money is working this winter to clear a channel 100-feet wide and 10-feet deep. The shallowest parts of the channel are only four-to-six feet deep now.

The busy Hatteras-Ocracoke ferry is supposed to run once every hour during winter months, from 5 a.m. to midnight. But the channel is impassable now at low tide, so the ferries stop running each day for four-to-eight hours out of the 19-hour schedule.

Ocracoke’s nearly 950 residents rely on the ferry for shopping trips, doctor’s appointments and routine errands from Hatteras to Manteo and Kitty Hawk. Now they plan their trips with tide tables in mind.

“We’re riding the ferry on the back side of high tide and the front side,” said Ocracoke businesswoman Darlene Styron, a Hyde County commissioner. “We’re having to schedule around the tides. You go anywhere during the day and you might as well pack your bag, because you might not get home that night.”

To help make up for the reduced service between Ocracoke and Hatteras, the Ferry Division has added a third daily round-trip run between Ocracoke and Swan Quarter.

If ferry and Corps of Engineers officials agree in February that Hatteras Inlet service needs to be shut down for a day or more, Thomas said, more trips will be added to the ferry schedules from Ocracoke to Swan Quarter and Cedar Island.

Siceloff: 919-829-4527 or blogs.newsobserver.com/crosstown or twitter.com/Road_Worrier/