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Natural Vegetation in the Central Valley of California

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Natural Vegetation in the Central Valley of California Natural Vegetation in the Central Valley of California Prepared for: STATE WATER CONTRACTORS AND SAN LUIS & DELTA-MENDOTA WATER AUTHORITY Technical Representative: Paul H. Hutton, Ph.D., P.E. Prepared by: Phyllis Fox, Ph.D., P.E. Lindsey Sears, M.A. June 2014 ACKNOWLEDGEMENTS This work was funded by San Luis Delta-Mendota Water Authority and the State Water Contractors. This work benefited greatly from discussions with and information provided by Dr. Robert F. Holland (unpublished vernal pool GIS shapefiles), as well as Rusty Griffin, U.S. Fish & Wildlife Service (historic wetlands map). This work was coordinated with other related tasks and reviewed by Dr. Paul Hutton (Metropolitan Water District). The final report was edited by Linda Standlee (State Water Contractors). Page i EDITORIAL NOTE: At the suggestion of the technical representative, Dr. Phyllis Fox agreed to include in this report (in three appendices) key documents she had previously prepared for the State Water Contractors in support of the 1987 State Water Resources Control Board Bay-Delta Hearings. Although some of these State Board exhibits have been superseded by the work presented in this report, it was agreed that the exhibits provide valuable background and historical perspective, and that inclusion of these exhibits in this report allows for wider access to the work. Page ii TABLE OF CONTENTS ACKNOWLEDGEMENTS .......................................................................................................... i 1.0 INTRODUCTION.............................................................................................................. 1-1 2.0 NATURAL HYDROLOGY .............................................................................................. 2-1 3.0 NATURAL VEGETATION .............................................................................................. 3-1 3.1 Other Floodplain Habitat ................................................................................................. 3-6 3.2 Grasslands ...................................................................................................................... 3-11 3.3 Vernal Pools ................................................................................................................... 3-15 3.3.1 Vernal Pool Topography ........................................................................................ 3-16 3.3.2 Vernal Pool Vegetation .......................................................................................... 3-19 3.3.3 Vernal Pool Hydrology .......................................................................................... 3-24 3.3.4 Vernal Pool Classification ..................................................................................... 3-30 3.3.5 Vernal Pool Acreage .............................................................................................. 3-35 3.4 Wetlands ........................................................................................................................ 3-53 3.4.1 Permanent Large-Stand Wetlands.......................................................................... 3-54 3.4.2 Permanent Small-Stand Wetlands.......................................................................... 3-55 3.4.3 Seasonal Wetlands ................................................................................................. 3-56 3.5 Valley/Foothill Hardwood ............................................................................................. 3-57 3.6 Riparian Vegetation ....................................................................................................... 3-60 3.7 Saltbush .......................................................................................................................... 3-63 3.8 Chaparral ........................................................................................................................ 3-63 3.9 Aquatic ........................................................................................................................... 3-64 4.0 Bibliography ....................................................................................................................... 4-1 TABLES Table 1. Monthly vegetation coefficients (Kv) for non-water stressed and rainfed vegetation ............................................................................................................. 3-4 Table 2. Initial Estimated Area of Natural Vegetation Av by Planning Area Within the Valley Floor, Case I (Acres) ................................................................................ 3-5 Table 3. Classification of Vegetation in CSU Chico (2003) "Other Floodplain Habitat" Based on Küchler (1977) (Acres) ........................................................................ 3-8 Table 4. Classification of Grasslands (acres) ............................................................................ 3-15 Table 5. Comparison of Vernal Pool Areas (Acres) ................................................................. 3-49 Table 6. Classification of Valley/Foothill Hardwoods (Acres) ................................................ 3-60 FIGURES Figure 1. Valley Floor Study Area .............................................................................................. 1-2 Figure 2. Natural Vegetation in the Valley Floor, Case I ............................................................ 3-3 Figure 3. Küchler Vegetation Classifications for CSU Chico Other Floodplain Habitat in Valley Floor ............................................................................................................... 3-6 Page i Figure 4. Lands Naturally Subject to Overflow Superimposed on CSU Chico "Other Floodplain Habitat" .................................................................................................... 3-7 Figure 5. SFEI Classification of CSU Chico Other Floodplain Habitat .................................... 3-10 Figure 6. Vernal Pool Microrelief ............................................................................................. 3-17 Figure 7. Formation of Vernal Pools ......................................................................................... 3-17 Figure 8. Vernal Pool Habitat Sequences ................................................................................. 3-21 Figure 9. Photographs of Vernal Pools of California ............................................................... 3-23 Figure 10. Flooded Vernal Pools. ............................................................................................. 3-25 Figure 11. Vernal Pool Habitat Under Natural Conditions....................................................... 3-36 Figure 12. Vernal Pool Soil Types ............................................................................................ 3-38 Figure 13. Comparison of Vernal Pool Maps ........................................................................... 3-46 Figure 14. Comparison of Vernal Pool Habitat Within Floodplain .......................................... 3-47 Figure 15. Wetland Extent in Central Valley in 1850s ............................................................. 3-50 Figure 16. Current Locations of Vernal Pools Based on Holland 1998 ................................... 3-52 Figure 17. Middle Fork Sacramento River in Delta 1852 ........................................................ 3-62 LIST OF APPENDICES Appendix A: Freshwater Inflow to San Francisco Bay under Natural Conditions Appendix B: Rebuttal to David R. Dawdy Exhibit 3 in Regard to Freshwater Inflow to San Francisco Bay under Natural Conditions Appendix C: Additional Evidence in Regards to Freshwater Inflow to San Francisco Bay under Natural Conditions Page ii 1.0 INTRODUCTION The author’s original work on natural landscape and hydrology was conducted for the State Water Contractors in support of the California State Water Resources Control Board’s Bay- Delta hearings in 1987. Key exhibits developed for these hearings are provided in these documents in Appendices 1 through 3. This report summarizes recent efforts to refine and update the original work produced in 1987. In related work, Delta outflow was estimated under the natural level of development and compared with Delta outflow under the current level of development. In both cases, the same climatic conditions were assumed to occur while varying the level of development that it encountered (natural vegetation and current conditions). (Fox et al. 20141). Natural conditions are defined as those that existed prior to 1769, the year livestock raising commenced, but assuming the climate of water years 1922 to 2009 (October 1921 to September 2009). Natural flows are calculated as a long-term annual average, assuming the climate of 1922 to 2009 repeats with the Valley Floor in a natural or undeveloped state, before livestock, flood control, levies, drainage, reclamation, irrigation, etc. These natural flows were calculated from a water balance expressed as: Delta Outflow = Water Supply - Water Use The water balance was calculated around the portion of the Central Valley that drains into San Francisco Bay, referred to as the "Valley Floor," shown in Figure 1. The boundary of the Valley Floor is defined by the drainage basins of the gauges used to determine rim inflows. Under natural conditions, the water supply was the sum of rim inflows and precipitation on the Valley Floor. The rim inflows are equal to the historically observed flows (or estimated historical flows),
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