Some homeowners in New Castle County may be subject to different flood insurance requirements starting next week, when an updated floodplain map that could impact insurance rates and development potential goes into effect.
The Delaware Department of Natural Resources and Environmental Control led efforts to revise the map along more than 96 miles of non-tidal streams in New Castle County— mainly in the Brandywine-Christina Watershed. DNREC officials say it has been accepted by the Federal Emergency Management Agency (FEMA).
Flood risks are generally increasing due to development of impervious surfaces. But some flood plains will shrink under the updated map as a result of more accurate ground elevation data.
Mike Powell of DNREC’s Shoreline and Waterway Program says parts of the currently effective map are based on studies up to 30 years old.
“One of the biggest problems with those older maps is that they had some pretty inaccurate elevation information," he said. "So you might have information about how much water is down the stream, but you don’t know who is going to get flooded because you don’t know how high the ground is in various locations.”
In a development called Newark Oaks off Route 273 near Newark, several parcels will be removed from the FEMA 100-year floodplain under the revised map. In a nearby neighborhood off E. Chestnut Hill Road, several parcels will be added to the FEMA 100-year floodplain.
“The maps were significantly inaccurate in certain areas," said Powell. "We would not generally even intend to remap a floodplain for the purpose of moving the line a few feet.”
Powell says homeowners affected by the flood insurance rate map changes were invited to information sessions.
The new map is effective Jan. 22. It is available online through DNREC.