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Upper Yakima River Comprehensive Flood Hazard Management Plan --2018 Cowiche Addendum

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Upper Yakima River Comprehensive Flood Hazard Management Plan --2018 Cowiche Addendum Upper Yakima River Comprehensive Flood Hazard Management Plan --2018 Cowiche Addendum-- ACKNOWLEDGEMENTS This Upper Yakima Comprehensive Flood Hazard Management Plan, 2018 Cowiche Addendum was prepared by Yakima County Public Services Water Resources Division with the assistance of citizens, stakeholder groups, landowners and agency representatives listed below. We thank them for the time and effort they spent improving the final product. UPPER YAKIMA RIVER CFHMP ADVISORY COMMITTEE (2017-2018) Voting Members Affiliation Mr. Scott Anfinson Washington State Department of Transportation Mr. Eric Bartrand Washington State Department of Fish and Wildlife Mr. David Brown City of Yakima Water/Irrigation Mr. Joseph Calhoun City of Yakima Planning Mr. Bruce Dekker Lake Aspen Homeowner’s Association Mr. Jeff Emmons Yakima County Office of Emergency Management Mr. Joel Freudenthal Yakima County Flood Control Zone District Mr. David Garretson Private Landowner Mr. Bob Ingham Private Landowner Mr. John Marvin Yakama Nation Ms. Keelan McPhee Yakima County Planning Division Mr. Mike Price City of Yakima Wastewater/Stormwater Mr. Bill Sauriol Washington State Department of Transportation Mr. Brett Sheffield City of Yakima Chief Engineer Ms. Katrina Strathman Mid-Columbia Fisheries Enhancement Group Alternates and Non-Voting Members Mr. Jason Clapp Yakima County Office of Emergency Management Mr. Mark Cleaver Yakima County Roads Maintenance Ms. Joan Davenport City of Yakima Community Development Mr. Glenn Denman Lake Aspen Homeowner Mr. Donald Gatchalian Yakima County Environmental Services Director Ms. Michelle Gilbert Washington Department of Ecology Mr. Byron Gumz Yakima County Planning Division Mr. Perry Harvester Washington State Department of Fish and Wildlife Mr. David Haws Yakima County Flood Control Zone District Mr. Terry Keenhan Yakima County Flood Control Zone District Mr. Dale Meck Yakima County Flood Control Zone District Ms. Margaret Neuman Mid-Columbia Fisheries Enhancement Group Mr. Connor Parrish Mid-Columbia Fisheries Enhancement Group Mr. Matt Pietrusiewicz Yakima County Engineer Mr. Scott Schafer City of Yakima Public Works Mr. Horace Ward Yakima County Office of Emergency Management i TABLE OF CONTENTS Title Page No. Acknowledgments .................................................................................................................... i Table of Contents ..................................................................................................................... ii List of Tables ............................................................................................................................. v List of Figures .......................................................................................................................... vi List of Abbreviations ............................................................................................................. vii Executive Summary ........................................................................................................... ES-1 CFHMP Requirements............................................................................................................ ES-1 Advisory Committee .............................................................................................................. ES-1 Hydraulic Analyses ................................................................................................................ ES-2 Recommended Actions .......................................................................................................... ES-6 1. Introduction ......................................................................................................................1 CFHMP Requirements.................................................................................................................. 1 Required Consultation with Other Agencies .................................................................. 1 Flood Hazard Management ............................................................................................... 8 Advisory Committee ........................................................................................................... 8 Goals and Objectives ......................................................................................................... 10 2. Growth Management Act .............................................................................................16 3. Background Data, Studies and Programs..................................................................19 Related Studies ............................................................................................................................ 19 Yakima County Revised Flood Insurance Study (2017) ........................................................ 22 Related Programs and Projects .................................................................................................. 27 Lower Naches River Partnership Projects (2005) .......................................................... 27 Lower Cowiche Channel Relocation Project (2013) ...................................................... 27 4. Flood History ..................................................................................................................30 Upstream Drainage and Regulation ......................................................................................... 30 Significant Cowiche Creek Floods ............................................................................................ 31 December 23, 1933 Flood............................................................................................................ 33 January 16, 1974 Flood ................................................................................................................ 34 February 1995 Floods .................................................................................................................. 35 February 9, 1996 Flood ............................................................................................................... 35 February 15, 2016 Flood ............................................................................................................. 36 March 6, 2016 Flood .................................................................................................................... 37 March 14-16, 2017 Flood ............................................................................................................. 37 5. Floodplain Infrastructure and Flood Control Facilities .........................................39 Creek Alignments........................................................................................................................ 39 Levees ............................................................................................................................................ 42 ii Highway and Road Crossings ................................................................................................... 43 U.S. 12 .................................................................................................................................. 43 U.S. 12 Bridge ..................................................................................................................... 44 City of Yakima Powerhouse Road Bridge ..................................................................... 44 Squire-Ingham Orchard Farm Bridge ............................................................................. 45 Railways and Trails ..................................................................................................................... 45 Cowiche Creek Trail Bridge ............................................................................................. 45 Irrigation Structures and Canals ............................................................................................... 45 Former U.S. 12 Gravel Pits ......................................................................................................... 45 6. Flood Issues and Infrastructure ..................................................................................47 Capacity of Cowiche Creek Infrastructure .............................................................................. 47 Hydraulic Modeling of Cowiche Creek Infrastructure Capacities ...................................... 47 2016/2017 Discharge Hydrographs .......................................................................................... 47 Hydraulic Simulations ................................................................................................................ 52 Downstream Impacts from Deficiencies of Cowiche Creek Infrastructure ........................ 53 100-yr Flood Routing in City of Yakima .................................................................................. 54 7. Generation of Alternatives and Recommendations ................................................58 Flood Preparation, Actions and Alternatives .......................................................................... 58 Near-Term Action Plans ................................................................................................... 58 Emergency Action Plan and Public Notification .................................................... 58 Memorandum of Understanding and Interlocal Agreements .............................. 58 Channel Cleanout ......................................................................................................
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