BRUNSWICK – Thousands of acres of midcoast clam flats are closed because the state failed to complete shoreline surveys that are required by the federal government.

More than 50 commercial clam diggers in the Boothbay Harbor region have not been able to dig clams on more than 5,600 acres of flats because of the lapse.

“We are really cornered right now,” said David Cheney, a clam digger from Bristol.

The flats were closed when officials learned that the staff person assigned to the region failed to complete the surveys, said David Etnier, deputy commissioner for the state Department of Marine Resources. The staffer, who was not named, retired in January.

The surveys must be completed every 12 years to comply with Food and Drug Administration and National Shellfish Program requirements. The surveys involve property-by-property assessments of potential pollution sources, such as failing septic systems or illegal washing machine discharges.

The FDA started to pressure the state last year when the missing surveys were discovered, Etnier said. The FDA has been monitoring the DMR’s shellfish program since 2004, citing concerns about understaffing, he said.

“From their point of view, this was unacceptable,” he said.

Etnier said the department suffers from a staffing shortage.

The surveys are done by employees, each of whom is responsible for overseeing about 1,000 miles of coastline or between six and 11 shellfish growing areas, Etnier said. Responsibilities include water quality testing, preparing annual reports, conducting shellfish studies, developing maps and meeting with clam industry workers.

“We are trying to get people not to focus on one person’s shortcomings, but on the bigger issue, which is the lack of staff and funding,” Etnier said.

Some other clam flats in Brunswick, Harpswell and Phippsburg were spared from being closed after officials spent much of last week going door to door at waterfront homes to complete the surveys. Those efforts have kept about 200 diggers in business.