Residents were frustrated on Tuesday night as representatives from the Federal Emergency Management Agency (FEMA) and its engineering partners at Camp Dresser and McKee explained why 166 properties in Marion, Mattapoisett, and Wareham were incorrectly identified in new floodplain maps.

The maps, which went into effect in July, were designed to identify the Plymouth County properties belonging in the high-risk flood zone known as Special Flood Hazard Areas, and those that were not. Residents in high-risk zones are required to purchase flood insurance.

Errors were found soon after the maps were released, leaving some residents confused about whether their property was indeed in the high-risk zone, and wondering whether they would need flood insurance.

Property owners whose land was incorrectly placed in the high-risk zone in July may be entitled to a refund on flood insurance, said FEMA representative Chris Markesich.

Others will now find their properties placed in the high-risk zone, and thus will need to purchase insurance.

In Marion, four areas were incorrectly identified as being included in the high-risk zone. Three areas in Mattapoisett were also included in this zone incorrectly, while one area in town will now be included in the high-risk zone.

During the hearing, frustrated residents sounded off about having to change flood insurance policies.

Mark Verity of Wareham said that due to the mapping errors, his home was incorrectly identified as being in a high-risk zone. Since then, Verity said he has paid for “expensive” flood insurance.

“I don’t know how they can justify putting me in this zone,” Verity said. “I live 150 yards away from water. I’m trying to investigate it myself. I don’t even know if I can trust FEMA. I don’t think it’s fair.”

While it is still unclear when the errors were made, CDM representative Tim Hillier said it likely occurred when the maps were being drafted.

“The errors are not from the engineering side, but there is analysis that went into the new mapping that has not been called into question,” Hillier said.

Letters of Map Revision will be sent out to those residents who were affected by the errors. After a 90-day waiting period, the revisions should go into effect by December, said Hillier.

“An error is an error and it’s impacting you in a negative way,” he said. “I apologize for that. We want to get this right as soon as possible.”

To submit comments related to the map revisions, contact Timothy Hillier, CDM Smith, 50 Hampshire Street, Cambridge, Ma 02139, HillierTS@cdmsmith.com.

To view the flood maps, visit FEMA's Map Service Center by clicking here.