2021-01-11-minutes-public-works-study-session

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�C hE ...'fp 7} , KIr=XWAL i CO DEPARTMENT OF PUBLIC WORKS MEMORANDUM TO: Cle Elum City Council and Mayor CC: Kittitas County Board of County Commissioners FROM: Mark Cook, Director, Public Works and Arden Thomas, Water Resource Manager DATE: January 5, 2021 SUBJECT: Crystal Creek Community Technical Partners Mapping SUMMARY • The Kittitas County Flood Control Zone District (FCZD) received funding from the Federal Emergency Management Agency (FEMA) to conduct a Crystal Creek Flood Study and to update the official maps used by FEMA and community officials based on the outcomes of the new study. Before initiating the study, the FCZD's hydraulic consultant met with members of the Cle Elum and Roslyn Communities to gather information about Crystal Creek flooding X$101KNOORA Compared to the original FEMA investigation conducted in the late 1970s, the new Crystal Creek study utilized better topographic and site condition information, including surveys of all stream crossings, and more advanced modeling techniques. • While FEMA has been updating the flood maps county -wide, the FEMA -led effort did not include any new studies for Crystal Creek. Changes to the Crystal Creek floodplain mapping as part of the FEMA -led effort is due to improved topography information. • The hydrologic and hydraulic study for Crystal Creek is complete. Within Cle Elum, the model results and proposed remapping indicate that there should be no expansion of the floodway designation and proposes minor revisions in areas currently mapped as within the 100 -year and 500 -year floodplains. • After the Letter of Map Revision application materials are finalized, it will need to be submitted by the three National Flood Insurance Communities (Cities of Cle Elum and Roslyn and Kittitas County) affected by the study and the proposed map changes. 411 N. Ruby St., Suite #1 TEL (509) 962-7523 Ellensburg, WA 98926 FAX (509) 962-7663