Ellensburg OKs Interlocal With Kittitas County to Update Flood Insurance Maps for Whiskey, Mercer Creeks
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Summary
City Council authorized an interlocal agreement with Kittitas County to submit updated FEMA flood-insurance maps (LOMR) for Whiskey and Mercer Creeks, adopting improved 2D hydraulic modeling, recent lidar and survey data and advancing a Whiskey Creek reroute feasibility study while reserving local discretion on advisory zone regulation.
Ellensburg — The City Council authorized the city manager to sign an interlocal agreement with Kittitas County on Dec. 15 to update FEMA Flood Insurance Rate Maps for Whiskey and Mercer creeks.
Rebecca Springer, the city’s water resources manager, said county and city teams integrated recent stormwater modeling, 2020 lidar, a 2025 drone survey and consultant analyses funded by FCAP and a stormwater capacity grant to produce updated two-dimensional hydraulic models. Dan Carlson, community development director, explained that maps inform regulatory floodplain designations and development standards such as base flood elevations and minimum elevation for the lowest floor.
Arden Thomas of the Kittitas County Flood Control Zone District described a roughly seven-mile study area and said the analysis identified areas where remapping could change regulatory designations. Staff emphasized that FEMA sometimes assigns an advisory (shaded Zone X) designation for broad, shallow-flood areas; under that approach, communities have discretion whether to apply heightened local building standards or require flood insurance, and advisory designations do not automatically trigger federally mandated flood-insurance purchase requirements for mortgages without a federal nexus.
The presentation also discussed a Whiskey Creek reroute feasibility analysis and potential levee certification considerations tied to the Reeser Creek levee expansion project. Presenters said some reroute scenarios could reduce flood risk in parts of the city while increasing risk in other areas, which would require working with affected property owners and evaluating off-site impacts. Staff recommended approval of the ILA to support a joint letter of map revision (LOMR) to FEMA and to enable coordinated outreach and updated regulatory data.
Council moved, seconded and approved authorization for the city manager’s signature on the ILA presented; the packet noted the county had already executed the agreement. Council recorded 'aye' votes and the motion passed.
Staff said next steps include finalizing the joint submittal to FEMA, continuing public outreach to explain advisory vs. regulatory classifications, and evaluating whether ordinance updates are required to reference new zone designations.
