Board allows Howerton family to build pool in mapped floodplain, requires hydraulic study

The Williamson County Board of Zoning Appeals on June 25 approved a variance permitting James and Heidi Howerton to construct an in-ground swimming pool within the mapped 100-year floodplain at 6713 Flat Creek Road, contingent on a hydraulic study that demonstrates the pool and related grading will not increase flood elevations or adversely affect downstream properties.

Jeff McCoy, planning staff, summarized the property and presented site photos. The Howertons told the Board they purchased the farm in 2019 believing the house itself was outside the floodplain based on the elevation certificate they received at closing; recent FEMA mapping revisions raised the base flood elevation (BFE) from about 714.0 feet to 714.6 feet and now include much of the rear yard. "We wouldn’t have purchased the property if we had known this in the beginning," Heidi Howerton said, explaining the family wants a pool so their children and grandchildren can swim where they can be closely supervised.

County Engineer Floyd Heflin told the Board the map change resulted from a limited-detail study and newer LiDAR topography that shows more of the parcel is within the floodplain. He recommended the homeowners either pursue a FEMA letter of map amendment or submit a hydraulic study; "with any encroachments they want to know that it will not have any adverse effects on adjacent properties," Heflin said. He noted FEMA will not automatically exempt a structure from flood insurance requirements unless the elevation certificate demonstrates the lowest adjacent grade and the structure are above the BFE.

Chairman Don Crohan expressed concern that an inground pool could alter flood flows and affect downstream properties. The Board voted to grant the variance under Sections 19.05(B)(2) and 5.02 of the Zoning Ordinance with the condition that the homeowners submit a hydraulic study showing the encroachment will not increase flood elevations by more than one foot and will not cause harm to neighboring properties. The motion to approve was made by Vice Chairman Andrew Ring and seconded by Matthew Roberts and passed by unanimous voice vote.

Next steps: the Howertons must commission the required hydraulic study and submit it as stipulated; staff and County Engineering will review the study before any permit is issued. The record shows the homeowners were required by FEMA to obtain flood insurance following the updated mapping.