Emergency management releases updated Provo River and Utah Lake flood‑risk study; public outreach planned

Jamie Huff, risk map program manager for the Utah Division of Emergency Management, told the Utah County Commission that maps last comprehensively updated in 1988 are being replaced with new hydrology, hydraulics and LIDAR data for the Provo River and Utah Lake.

"The maps are from '88, so they're very old," Huff said, noting the team completed field surveys, updated flow models and tied tributary river analyses into the lake study. In the Provo River analysis the project team could not locate documentation showing the levee was accredited; as a result FEMA maps will model the levee as uncertified and show that parts of the river corridor will no longer be protected to the 1% annual‑chance flood standard.

Huff said efforts reduced modeled flows from the older studies in some reaches by nearly 1,000 cubic feet per second, which lowered upstream floodplain extents in places. For Utah Lake, the team added a shoreline hazard analysis — described on FEMA maps as a VE or coastal zone — to account for wind‑driven waves; Huff said modelled wave heights of about 1½ feet affected the new shoreline limits.

The presentation spelled out next steps: the team expects to release preliminary FEMA Flood Insurance Rate Maps (FIRMs) later this fall, followed by a public notice and due‑process period for appeals. Huff said the maps generally take about 18 months from preliminary release to become effective because of the notice and adoption windows. She said the project has a public outreach plan that includes targeted meetings in Provo, fact sheets, a project website and press notices.

Commissioners asked how affected homeowners would be notified. Huff said lenders will be notified for mortgaged properties and that the division will work with local officials to provide outreach; she also emphasized that purchase of flood insurance is highly encouraged for properties newly placed in the floodplain, whether or not a mortgage requires it.

The division credited local stakeholders — including the Central Utah Water Conservancy District and Utah County staff — for technical collaboration and encouraged residents and officials to consult the project website and forthcoming open houses for details and appeal instructions.