NOVATO CREEK HYDRAULIC STUDY ANALYSIS OF ALTERNATIVES PREPARED FOR: County of Marin Department of Public Works BY: Kamman Hydrology & Engineering, Inc. 7 MT. LASSEN DRIVE, SUITE B250 San Rafael, CA 94903 (415) 491-9600 IN ASSOCIATION WITH: WRECO 1243 Alpine Rd, Suite 108 Walnut Creek, CA 94596 June 2016 Novato Creek Hydraulic Study: Alternatives Development and Hydraulic Analysis Final Report: June, 2016 Services provided pursuant to this Agreement are intended for planning purposes for the The Marin County Department of Public Works i‐1 Novato Creek Hydraulic Study: Alternatives Development and Hydraulic Analysis Final Report: June, 2016 TABLE OF CONTENTS Page No. 1 EXECUTIVE SUMMARY ................................................................................................................... ES‐1 1.1 Summary of Study Alternatives: .............................................................................................. ES‐3 Short Term Alternative: .................................................................................................... ES‐4 Medium Term Alternative: ............................................................................................. ES‐10 Long Term Alternative: ................................................................................................... ES‐14 1.2 Alternatives Analysis .............................................................................................................. ES‐18 1.3 General Flood Study Findings ................................................................................................ ES‐22 1.4 Alternative Analysis Conclusions ........................................................................................... ES‐26 Short Term Elements: ..................................................................................................... ES‐26 Medium Term Elements: ................................................................................................ ES‐27 Long Term Elements: ...................................................................................................... ES‐27 1.5 Sea Level Rise Impacts ........................................................................................................... ES‐28 1.6 Recommendations ................................................................................................................. ES‐28 Priorities for Next Phases of Work ................................................................................. ES‐28 Additional Projects: ........................................................................................................ ES‐28 ............................................................................................................ ES‐29 2 INTRODUCTION ................................................................................................................................ 2‐1 2.1 Physical Setting .......................................................................................................................... 2‐3 2.2 Approach .................................................................................................................................... 2‐5 3 STUDY ELEMENTS AND RANKING ................................................................................................... 3‐1 3.1 Project Elements Determination ............................................................................................... 3‐1 3.2 Project Elements Evaluation: The Criteria Development and Ranking Process ........................ 3‐8 4 STUDY ALTERNATIVES ..................................................................................................................... 4‐1 4.0 Study Alternatives Overview: .................................................................................................... 4‐1 4.1 Short Term Alternative Elements: ............................................................................................. 4‐2 4.2 Medium Term Alternative: ...................................................................................................... 4‐11 4.3 Long Term Alternative Elements: ............................................................................................ 4‐19 5 ALTERNATIVES ANALYSIS ................................................................................................................ 5‐1 5.1 Alternatives Analysis of Design Storms ..................................................................................... 5‐2 Medium Term Alternative Analysis Summary .................................................................. 5‐19 Long Term Alternative Analysis ........................................................................................ 5‐30 5.2 Comparison of Short Medium and Long Term Altenatives ..................................................... 5‐42 5.3 Alternatives Analysis of Sea Level Rise Impacts ...................................................................... 5‐55 5.4 Alternative Analysis of Mid‐Tide Scenarios ............................................................................. 5‐56 6 NPW STUDY CONCLUSIONS ............................................................................................................. 6‐1 6.1 General Findings: ....................................................................................................................... 6‐1 6.2 Alternatives Analysis Conclusions .............................................................................................. 6‐4 Short Term Alternative Elements: ...................................................................................... 6‐4 Medium Term Elements: .................................................................................................... 6‐5 i‐2 Novato Creek Hydraulic Study: Alternatives Development and Hydraulic Analysis Final Report: June, 2016 Long Term Elements: .......................................................................................................... 6‐5 6.3 Recommendations ..................................................................................................................... 6‐6 Recommendations for Next Phases of Work ..................................................................... 6‐6 Additional Project Elements: .............................................................................................. 6‐6 Concepts Recommended for Additional Study: ................................................................. 6‐6 LIST OF APPENDICES Attachment A: Participating Stakeholders Attachment B: Study Elements Attachment C: Element Ranking Criteria Attachment D: Creek Modeling Results Attachment E: Bayland Modeling Results i‐3 Novato Creek Hydraulic Study: Alternatives Development and Hydraulic Analysis Final Report: June, 2016 LIST OF FIGURES Page No. Figure ES‐1: Short Term Alternative Elements ....................................................................................... ES‐6 Figure ES‐2: Q50 Short Term Results for Novato Baylands .................................................................... ES‐8 Figure ES‐3: Q50 ‐ Existing and Short Term Alternative Water Surface Elevation at MAX Flood .......... ES‐9 Figure ES‐4: Medium Term Alternative Elements ................................................................................ ES‐11 Figure ES‐5: Q50 Medium Term Results for Novato Creek .................................................................. ES‐12 Figure ES‐6: Q50 ‐ Existing and Medium Term Alternative Water Surface Elevation at Max Flood .... ES‐13 Figure ES‐7: Long Term Alternative Elements ...................................................................................... ES‐15 Figure ES‐8: Q50 Long Term Results for Novato Creek ........................................................................ ES‐16 Figure ES‐9: Q50 ‐ Existing and LONG Term Alternative Water Surface Elevation at Max Flood ........ ES‐17 Figure ES‐10: Q50 Peak Water Surface Profile – Diablo Ave. to San Pablo Bay (ft, NAVD88) ............. ES‐19 Figure ES‐11: Q50 Peak Flood Water Surface Elevations (Plan View) .................................................. ES‐21 Figure ES‐12: Q50 Peak Flood WSE Profiles – Existing Conditions and with 1‐ft and 3‐ft of Sea Level Rise .............................................................................................................................................................. ES‐22 Figure 2 1: Novato Creek Watershed Topography and Drainages. .......................................................... 2‐3 Figure 2 2: Novato Creek Channel Incision (left) and Bayland Deposition (right) ................................... 2‐4 Figure 2 3: Boundaries of the integrated models .................................................................................... 2‐6 Figure 2 4: Boundaries and bathymetry (a. above) and model mesh (b. below) of the NHS Bayland Model ....................................................................................................................................................... 2‐8 Figure 4 1: Short‐Term Alternative Elements ........................................................................................... 4‐6 Figure 4 1a: Short Term Element 3, Restoration of Leveroni Creek Tributary Floodplain ....................... 4‐7 Figure 4 1b: Short Term Elements 5‐6 ...................................................................................................... 4‐8 Figure 4 1c: Short Term Elements