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KITTITAS COUNTY <br />DEPARTMENT OF PUBLIC WORKS <br />PUBLIC WORKS — BOARD OF COUNTY COMMISSIONERS <br />STUDY SESSION STAFF REPORT <br />STUDY SESSION DATE: September 14, 2026 <br />TOPIC: Yakima River at Easton Flood Risk Categories <br />ACTION REQUESTED: Direction to staff <br />LEAD STAFF: Arden Thomas <br />RECOMMENDATION: Direct staff to work with the National Weather <br />Services to update flood risk categories. <br />BRIEFING SUMMARY: <br />• The National Weather Service uses flood risk categories to communicate how <br />severe flooding is expected to be at a particular location. <br />• The Elk Meadows, Elk Meadows II, Pine Glen, and Sun Island communities are <br />our most at -risk flood communities. While river forecasting is available for this <br />area, flood risk categories for moderate and major flood stages have not been <br />identified. <br />• The National Weather Service has requested that Kittitas County provide input on <br />flood risk categories. <br />• Recent investments in hydraulic modeling have enabled us to provide more <br />informed feedback. <br />• If the NWS updates the flood risk categories, we recommend reaching out to <br />Easton Reach area residents to inform them about the availability of river forecast <br />and information. <br />BACKGROUND: <br />The U.S. Bureau of Reclamation maintains a river gage at Easton (EASW) that measures <br />the Yakima River's water level. The Northwest River Forecast Center (National Oceanic <br />and Atmospheric Administration, National Weather Service) displays observed river <br />levels and develops and displays a 7-day river forecast. The National Weather Service <br />(NWS) also shows flood risk categories to help identify and communicate the anticipated <br />severity of a forecasted flood event. <br />The Elk Meadows, Elk Meadows II, Pine Glen, and Sun Island communities are our most <br />at -risk flood communities. While river forecasting is available at the EASW gage, this <br />area currently lacks flood risk categories. After the December 2025 flood, the National <br />Weather Service requested that Kittitas County provide input on flood risk categories. <br />The NWS utilizes the following flood risk categories: <br />Page 1 of 4 <br />PUBLIC WORKS BOARD OF COUNTY CONMSSIONERS WORK SESSION STAFF REPORT <br />