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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 28, 2026 <br /> TOPIC: Gladmar Reach Flood Impacts <br /> ACTION REQUESTED: Direction to Staff <br /> LEAD STAFF: Arden Thomas <br /> RECOMMENDATION: Direct staff to conduct initial technical evaluation <br /> and scoping potential partnerships to inform next <br /> steps <br /> BRIEFING SUMMARY: <br /> • The Cascade Irrigation District recently notified Public Works that Yakima River <br /> channel changes associated with the December 2025 flooding are affecting its <br /> ability to divert irrigation water. The flooding also caused erosion along the <br /> Washington State Parks Palouse to Cascade Trail. <br /> • The historical record indicates that infrastructure within this area is vulnerable to <br /> flooding, channel migration, and erosion. <br /> • Additional work is needed to identify potential remedies, evaluate permitting <br /> considerations, and estimate the costs of potential improvements. <br /> • Given the history of channel changes and flood impacts in this area, flood control <br /> measures may not deliver permanent solutions. <br /> BACKGROUND: <br /> The Cascade Irrigation District recently notified Public Works that channel changes <br /> resulting from the December 2025 flooding are affecting its ability to divert irrigation <br /> water. The altered channel became problematic later in the irrigation season when <br /> Reclamation implemented its annual "flip-flop" operation, which substantially decreases <br /> Upper Yakima River flows. Drone footage obtained by the Kittitas County Conservation <br /> District has also identified significant erosion along the Washington State Parks Palouse <br /> to Cascade ("PTC") Trail. Kittitas County Public Works has contacted State Parks and <br /> has reached out to the Washington State Department of Transportation because I-90 is <br /> adjacent to the PTC Trail. <br /> These flood impacts occurred within the Gladmar Reach of the Yakima River, in the <br /> vicinity of the former Gladmar gravel pit and Kittitas County park. Research indicates a <br /> history of significant channel changes and flood impacts in this area. In 1964, the <br /> Packwood diversion dam, which supplies water to Packwood Ditch, was breached. In <br /> 1996, flooding destroyed Gladmar Park, a County-owned facility, and the section of <br /> Page I of 4 <br /> PUBLIC WORKS BOARD OF COUNTY COMMISSIONERS WORK SESSION STAFF REPORT <br />