Laserfiche WebLink
KITTITAS COUNTY <br />DEPARTMENT OF PUBLIC WORKS <br />PUBLIC WORKS — BOARD OF COUNTY COMMISSIONERS <br />STUDY SESSION STAFF REPORT <br />STUDY SESSION DATE: January 11, 2021 <br />TOPIC: Crystal Creek Flood Study and Map Updates <br />ACTION REQUESTED: Direction to Staff <br />LEAD STAFF: <br />Arden Thomas <br />RECOMMENDATION: <br />Direct staff to submit finalized Letter of Map Revision Application and conduct outreach. <br />BRIEFING SUMMARY: <br />• The Kittitas County Flood Control Zone District (FCZD) received funding from <br />the Federal Emergency Management Agency (FEMA) to conduct a Crystal Creek <br />Flood Study and to update the official maps used by FEMA and community <br />officials based on the outcomes of the new study. <br />• FCZD staff has been coordinating with Cle Elum and Roslyn Communities to <br />gather information about Crystal Creek flooding concerns and integrate this study <br />with Roslyn's stormwater planning and capital improvement efforts. <br />• Compared to the original FEMA investigation conducted in the late 1970s, the <br />new Crystal Creek study utilized better topographic and site condition <br />information, including surveys of all stream crossings, and more advanced <br />modeling techniques. <br />• While FEMA has been updating the flood maps county -wide, the FEMA -led <br />effort did not include any new studies for Crystal Creek. Changes to the Crystal <br />Creek floodplain mapping as part of the FEMA -led effort is due to improved <br />topography information. <br />• The hydrologic and hydraulic study for Crystal Creek is complete. Within Cle <br />Elum, the model results and proposed remapping indicate that there should be no <br />expansion of the floodway designation and proposes minor revisions in areas <br />currently mapped as within the 100 -year and 500 -year floodplain. <br />• After the Letter of Map Revision application materials are finalized, it will need <br />to be submitted by the three National Flood Insurance Communities (Cities of Clc <br />Elum and Roslyn and Kittitas County) affected by the study and the proposed <br />map changes. <br />Page I of 9 <br />PUBLIC WORKS BOARD OF COUNTY COMMISSIONERS WORK SESSION STAFF REPORT <br />