Pájaro River Watershed Flood Protection Plan - The Pajaro River ...

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FIGURES AND PLATES Fig 1 Map of Lower Pájaro River and Elkhorn areas showing historical changes Fig 2 Historical aerial photo of Pájaro Valley showing landslides Map A Rancho Vega del Rio Pájaro and Northern Monterey County 1875 Map B Land Ownership in Vega area about 1910 Fig 3 Historical (1938) aerial photo showing past breakout areas Fig 4 Historical (1938) aerial photo showing meander wavelength in lower valley Fig 5 Map of Pleistocene Lake San Benito (from Jenkins) Fig 6 Calculated flood discharge frequency/magnitude plot at Chittenden Fig 7 Monterey Herald photograph of 1938 Lower Pájaro flooding Map C FEMA 100-year flood map and map of areas considered for flood storage augmentation in this report Fig 8 Soil profile in active overbank storage areas Fig 9 Lake San Benito soil profile Fig 10 Example of area that can be restored to flood storage Fig 11 Effects of channel incision on channel stability and habitat Fig 12 Cienega Road House Fig 13 Llagas Creek Channel photos Fig 14 Gabion Basket representation Fig 15 Stream Barb representation with Gabion Baskets Fig 16 Detailed topography of a portion of Lower San Benito River near Highway 101 Fig 17 San Benito River Channel topography near Mitchell Road APPENDICES App 1. Note on higher recorded 1998 flow at Highway 156 than downstream at Chittenden gauge from L. Freeman, USGS App 2. Analysis of 1998 and 1995 storm conditions with map of precipitation stations used in the analysis App 3. Streambank property owners in San Benito County (separate file) App 4. In preparation App 5. Example of Historical Changes in Lower San Benito River (Figs 18-21) App 6. Topographic detail for a cross section in the App 5. Historical Change area App 7. Mines in the San Benito County permit files (separate file) App 8. Economics and Socioeconomic Settings DRAFT 7/22/03 4 Pájaro Watershed Flood Management
Pájaro River Watershed Flood Management Alternatives A study by the CSUMB Watershed Restoration Class, Spring 2003 CHAPTER 1 Introductory Context This report is a group effort of 12 upper level students who have focused much of their education on Watershed Science through the Earth Systems Science and Policy Program at California State University Monterey Bay. Some participants had already graduated from CSUMB or UC Santa Cruz; while most were finishing seniors with educations that included advanced hydrology, water law, and riparian ecology. CSU Monterey Bay stresses an “outcomes-based” education with active, applied learning. This work is not financially supported, but a small anonymous donation of $500 helped with copying and telephone costs. The Santa Clara Valley group “People for Livable and Affordable Neighborhoods” supported a detailed watershed map made especially for this effort by Eureka Cartography in Berkeley. San Benito County and the Graniterock Company contributed map and data resources. This report follows the theme of our educational program and treats the Pájaro Watershed as a physical and biological system. We take the position that it is not possible to isolate the processes and problems in the lower watershed from the causal mechanisms in the upper watershed. We look at the watershed as a complete system with material and energy flows that support living ecosystems and organisms. We assess the causes of dysfunction, which in this particular case focuses on responses of humans to flooding and sediment transport, and evaluate potential solutions utilizing fundamentals of fluvial geomorphology and restoration ecology. This particular study was undertaken in the context of significant fundamental disagreements between residents, agencies, and government entities. Following the California Supreme Court finding that upheld lower court’s rulings against County governments for causing flooding in 1995 through lack of required maintenance, Monterey and Santa Cruz counties requested that the U.S. Army Corps of Engineers consider a new flood control project to protect the downstream areas from 100-year return-period floods. This class effort focused on the opportunities to reduce downstream flood hazards through upstream flood detention and through design of a stable channel alternative in the artificially constrained lower reaches of what is called the Pájaro Valley. DRAFT 7/22/03 5 Pájaro Watershed Flood Management
Page 1 and 2: California State University Robert
Page 3: Table of Contents Executive Summary
Page 7 and 8: that today bears the name Pájaro.
Page 9 and 10: Map B. 1908 Parcel Map of a portion
Page 11 and 12: Map A 1875 based on 1854 land surve
Page 13 and 14: Upper Watershed, San Benito and San
Page 15 and 16: Himalaya and Alaska are there possi
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Page 19 and 20: The current project attempts to rec
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Page 27 and 28: value for the maximum possible 100-
Page 29 and 30: Regional Analysis The trend in perc
Page 31 and 32: Interestingly, the maximum consecut
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Page 41 and 42: clearly attenuate (reduce) flood pe
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Page 49 and 50: APPENDICES & Figures APPENDIX 1: No
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50 Corralitos Creek Hydrograph & Co
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Figure 16 - San Benito River channe
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Fig 15 Stream Barb Structures DRAFT
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Corps’ Data presented Alternative
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California State University Robert
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. illustrations, on an interim repo
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APPENDIX 3 Streambank Property Owne
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Historical Change in San Benito Riv
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