PORTLAND — New federal flood zone maps raise as many questions as they answer, officials in Scarborough and South Portland said this week.

Three years after it withdrew a set of high-tech maps showing flood hazards in Cumberland and York counties, the Federal Emergency Management Agency  released a new set Nov. 5.

The preliminary flood insurance rate maps, or FIRMs, are online in South Portland and Scarborough, but Scarborough Assistant Planner Jay Chace and South Portland Community Planner Steve Puleo said the total number of properties affected by flood zone designations has not been tabulated.

Chace estimated Wednesday at least 1,000 Scarborough properties could be involved. Puleo said as many as 75 properties in South Portland could be included in new wave zone designations.

The maps, which can also be found on FEMA’s website, will be discussed at a series of public meetings to be scheduled in January.

“Because there have been changes, we really encourage people to take a look and understand what (the new maps) mean,” said Kerry Bogdan, the FEMA senior engineer who oversees the mapping project in Maine.

The good news, according to Scarborough Manager Tom Hall, Chace and Puleo, is the revised maps better incorporate data for potential wave velocity and possible flood zones compiled several years by engineer Bob Gerber, then with Sebago Technics.

Gerber was asked to make more detailed studies in southern Maine communities after FEMA issued preliminary FIRMs in 2009 that provoked criticism from the public. In several communities, homeowners and business people complained about miscalculations in the mapping that mistakenly placed their properties in higher-risk flood zones.

That, in turn, can translate into higher insurance and mortgage costs.

The bad news, Hall said, is the new maps still do not accurately depict the flood potential of the Scarborough Marsh, especially regarding wave velocity.

“This is the third time they have been released, and frankly, it is still a mess,” Hall said at Wednesday’s Town Council meeting. “The implications of these changes can be severe on certain properties.”

Projections of velocity zones suggesting waves could wash upriver beyond the Pan-Am railroad tracks has the town again enlisting Gerber, now with Portland-based Ransom Consulting Engineers & Scientists, for a $25,000 mapping study of potential marsh flood zones.

“They are building models that don’t exist,” Hall said.

The data could become part of the appeals process, and Hall said it remains to be seen if he will file an appeal on behalf of the town. An unanswered question is whether a municipal appeal would prevent any private appeals from residents.

The FIRMs could have a huge impact on property owners throughout the region, since the maps are used to determine who is legally required to buy flood insurance – which can cost thousands of dollars a year – and where building development may be restricted because of flood potential.

In general, the new maps extend southern Maine’s flood zones inland, placing more properties in high-risk “special flood hazard areas.”

For example, the mapping analysis, which takes into account factors such as topography, water depth and wind speed, now considers the impact of a flood’s largest waves. Previously, waves of average height were considered.

Despite the expansion of the flood zones, residents may find individual homes or businesses are now in zones with less flood risk than indicated by current FEMA maps, some of which are 30 years old.

The new maps incorporate feedback from the previous try, and should be “better overall,” said Joe Young, mapping coordinator for the Maine Floodplain Management Program, which works with FEMA.

But Young admitted that no map is perfect.

“The trouble with the maps is that they’re based on a modeled event. They’re done with a scientific approach, but they’re not a reflection of any one storm,” he said.

“So there’s always room in the model for mistakes. Especially when you have a coastline as complicated and irregular as Maine’s, it’s difficult to get things exactly right.”

Following the public meetings, there will be a 90-day period in which property owners and municipalities may comment on the maps or appeal their classifications. After any changes to the maps are made, FEMA expects them to be finalized by the summer of 2015.

Hall said he would like to have local meetings, and Puleo said he is working on more precise printed maps, while looking to notify local property owners affected by the changes.

Puleo said city Code Enforcement Officer Patricia Doucette is looking into what possible building code changes might be needed in affected zones.

In Scarborough, councilors last year shelved proposed zoning changes requiring new construction of substantially reconstructed properties in flood zones to be elevated three feet above the tide line.

Hall said those changes will not be discussed until the maps are finalized.

Staff writer William Hall contributed to this report. David Harry can be reached at 781-3661 ext. 110 or dharry@theforecaster.net. Follow him on Twitter: @DavidHarry8.

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The boat landing at Clay Pits Road in Scarborough, seen Wednesday, Nov. 20, is included in a wave velocity zone in FEMA flood maps released Nov. 5.

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