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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: <br />TOPIC: <br />ACTION REQUESTED: <br />September 28, 2026 <br />Gladmar Reach Flood Impacts <br />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 1 of 4 <br />PUBLIC WORKS BOARD OF COUNTY CONINUSSIONERS WORK SESSION STAFF REPORT <br />