Sharonville Council approves funds for 2D floodplain remapping after debate over FEMA modeling

Sharonville City Council on June 23 approved an emergency ordinance to fund additional hydraulic mapping and to submit a Letter of Map Revision (LOMR) to FEMA, a step city staff said is needed to refine downtown floodplain lines after bridge and dam improvements.

Safety Service Director Mr. Lucas told council that the city’s consultant, Tetra Tech, recommended moving from a one-dimensional to a two-dimensional model to use more of the local topographic detail — curbs, crowns and streets that act as drainage channels — and thereby provide a more accurate depiction of where water would spread. "The two-dimensional model will allow us to use more of the topographic data that we have," Lucas said, adding that the approach "will be a more accurate map as to where the water would actually be." He cautioned, however, that the city cannot guarantee how FEMA will rule on the final map.

Council members pressed staff on why the two-dimensional mapping was not done earlier. Staff said earlier modeling and grant decisions were based on older FEMA assumptions and that FEMA later required different parameters — for example, accounting for two creeks that influence downtown flooding — which expanded the floodplain shown by the one-dimensional model. One council member framed the choice as an ethical obligation to use the best available data. Another asked about the practical implications: if the revised map is accepted, affected properties would be placed in the 100-year flood zone and owners with federally backed mortgages "would be required to have flood insurance," Mr. Cox said.

The ordinance appropriates funds from the city’s capital fund and authorizes the Safety Service Director to sign necessary professional-services agreements to complete the hydraulic mapping and pursue the LOMR with FEMA. Council member Mr. Cook made the motion to approve; Ms. Cittadino seconded. Roll call showed six votes in favor and one recusal: Mr. Cox abstained and recused himself, citing a possible economic impact on his residence. The ordinance passed.

City staff said the 2D model should provide more geographically precise results and that the city will return later in the fall with the formal resolution accepting amounts and rates tied to the budget process. There is no certainty that FEMA will accept every proposed map change; staff and the consultant said the federal review can add time to the process.

Next steps: staff will complete the two-dimensional hydraulic mapping, submit the LOMR materials to FEMA and report back to council on any changes and the timetable for final adoption of budget amounts that follow from this mapping work.