Benton County weighs FEMA pre‑implementation measures and floodplain mapping updates

Benton County’s Community Development department on Sept. 17 updated the Board of Commissioners on ongoing floodplain mapping work and new FEMA‑related requirements tied to the Endangered Species Act.

Toby Lewis said the county is participating in two mapping projects—the Lacomb watershed and the Upper Willamette watershed—that together will cover Benton County. Preliminary map review is expected in the 2026–27 timeframe, Lewis said, and FEMA will provide draft maps for public comment.

Lewis also reviewed FEMA’s pre‑implementation compliance measures (PICM), which FEMA has described as short‑term steps communities must take before final ESA‑related rules are adopted. The county summarized three PICM approaches: prohibit development in mapped floodplains; adopt FEMA’s model ordinance that includes mitigation for three floodplain functions (flood storage, impervious surface and tree quantity/size); or evaluate development permit‑by‑permit with required habitat assessments.

Lewis told commissioners many communities are asking for more time to meet the PICM January notification and implementation deadlines. She said the county is reviewing impacts such as whether ordinance adoption would trigger Measure 56 notice requirements and potential housing impacts. Commissioners raised concern about the scale of riparian buffers under the guidance (a 70‑foot buffer on each side of a stream was discussed) and the effects on private landowners; staff said the 70‑foot figure is a starting point and communities may document smaller setbacks if supported by studies.

Lewis asked for guidance on the preferred meeting type to discuss PICM and related ordinance options; commissioners signaled interest in a goal‑setting or workshop session to dig into mitigation, potential mitigation banking and regional partnership options. The board requested continued updates as FEMA’s guidance and timelines evolve.