2016 Water Inventory and Analysis Report Highlights on

2016 Water Inventory and Analysis Report Highlights on Land Use, Water Supply, and Water Budgets Christina Buck, Ph. D Water Resources Scientist Board of Supervisors August 23, 2016 Water Inventory and Analysis Report August 23, 2016 1

Background • Update to 2001 Water Inventory and Analysis Report (WI&A) • Butte Basin Groundwater Model • Refinements to inputs to better represent historical hydrologic conditions • Accounting of supplies and demands 20002014 Water Inventory and Analysis Report August 23, 2016 2

WI&A Report Highlights I. Land Use: How has it changed since 2000? (Section 3) II. A View of the County Through Differing Water Supplies (Section 4) III. Water Budgets Help Tell a Story (Section 5) Water Inventory and Analysis Report August 23, 2016 3

Note on Uncertainty • Updates to the BBGM and WI&A rely on the best available information • All data and estimates are subject to uncertainty • Trends and differences are more reliable than absolute numbers Water Inventory and Analysis Report August 23, 2016 4

Part I. How has land use changed since 2000? A. Total irrigated agricultural acreage has been remarkably stable since 2000 A. Significant land use changes have occurred but mostly related to crop shifts Water Inventory and Analysis Report August 23, 2016 5

County-Wide Land Use • DWR surveys from 1994, 1999, 2004, 2011 • Identifies land use, water source, and other attributes • High spatial detail • Annual changes estimated from ag. commissioner crop reports through 2014 Water Inventory and Analysis Report August 23, 2016 6

Valley Floor General Land Use 500 450 Acres (Thousands) 400 Irrigated Agriculture Non-Irrigated Wetlands Developed 42 26 44 29 47 30 50 30 148 144 141 137 236 234 235 1995 -1999 2000 -2004 2005 -2009 2010 -2014 350 300 250 200 150 100 50 0 Water Inventory and Analysis Report August 23, 2016 7

Total irrigated agricultural acreage relatively stable since 2000 Acres (Thousands) 250 Rice Orchards Other Cropland 15 16 200 30 150 Idle Cropland 29 14 20 20 18 85 89 94 97 105 101 106 101 1995 -1999 2000 -2004 2005 -2009 2010 -2014 100 50 0 Valley Floor Irrigated Land Use Water Inventory and Analysis Report August 23, 2016 8

Increasing orchard acreage and recent shift to walnuts 120 Almonds Walnuts Prunes Other Trees and Vines Acres (Thousands) 100 80 9 11 10 10 23 27 35 40 39 40 38 37 1995 -1999 2000 -2004 2005 -2009 2010 -2014 9 13 60 9 13 40 20 0 Valley Floor Orchard Land Use Water Inventory and Analysis Report August 23, 2016 9

Orchards Replacing ‘Other Crop’ Acreage 35 Grain Pasture and Alfalfa Field and Annual Acres (Thousands) 30 25 7 8 20 15 4 12 14 13 10 5 0 3 11 1995 -1999 7 2000 -2004 11 4 3 2005 -2009 2010 -2014 Valley Floor ‘Other Crop’ Land Use Water Inventory and Analysis Report August 23, 2016 10

VINA WEST BUTTE EAST BUTTE NORTH YUBA Water Inventory and Analysis Report August 23, 2016 11

Land Use Summary • Land use relatively stable since 2000 • Valley Floor developed lands increased approximately 7, 000 acres between 2000 and 2014 • Orchards have shifted from almonds and prunes to walnuts • Overall increase in orchards is offset by decreases in other, non-rice crops Water Inventory and Analysis Report August 23, 2016 12

Part II. A View of the County Through Differing Water Supplies Water Inventory and Analysis Report August 23, 2016 13

Water Sources • Precipitation (914 TAF) • Applied Surface Water (715 TAF) • Groundwater Pumping (411 TAF) = 2. 04 MAF Water Inventory and Analysis Report August 23, 2016 14

Large Variations in Streamflow Water Inventory and Analysis Report August 23, 2016 15

Relatively Stable Surface Water Diversions 1 000 Feather River Ag Butte Creek Ag Sacramento River Ag Other Ag Developed 900 000 Annual Diversions (af) 800 000 700 000 600 000 500 000 400 000 300 000 200 000 100 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Water Year Water Inventory and Analysis Report August 23, 2016 16

Groundwater Pumping Variable by Water Year Type Wide range, depending largely on year type. Little correlation with time. Water Inventory and Analysis Report August 23, 2016 17

Pumping by Water Demand Type: Valley Floor 8% 1% 91% Irrigated Agriculture and Wetlands M&I (31 taf) Rural Residential (5 taf) Water Inventory and Analysis Report August 23, 2016 (374 taf) 18

Well Infrastructure Water Inventory and Analysis Report August 23, 2016 19

Well Infrastructure Water Inventory and Analysis Report August 23, 2016 20

Water Supplies Summary • Highly variable precipitation and resulting streamflows from year-to-year • Relatively steady surface water supplies due to senior water rights and settlement contracts, despite year-to-year differences in precipitation • Variability in precipitation is a driver of yearto-year differences in groundwater pumping Water Inventory and Analysis Report August 23, 2016 21

Part III. Water Budgets Help Tell a Story Where does the water come from and where does it go? Water Inventory and Analysis Report August 23, 2016 22

Land Surface Water Budgets Inflows – Outflows ± Change in Storage = 0 Precipitation Surface Water Deliveries Subsurface Inflows Evapotranspiration Land Surface (Ag, urban, or native land use) Groundwater Pumping Runoff and Return Flow Accretions/ Deep Percolation Depletions Subsurface Outflows Groundwater System Water Inventory and Analysis Report August 23, 2016 23

Land Surface Water Budgets • Valley floor inventory units (and subinventory units) • Overall and by general land use • Irrigated agriculture and wetlands • Developed lands • Non-irrigated lands Water Inventory and Analysis Report August 23, 2016 24

Valley Floor Overall Water Budget Average Annual Inflows and Outflows (thousands of acre-feet) Water Inventory and Analysis Report August 23, 2016 25

Valley Floor Average Annual Water Budgets Total Inflow/ Outflow 2, 040 taf Irrigated Ag. /Wetlands (1, 587 taf) Developed Lands (140 taf) Non-Irrigated Lands (312 taf) DRAFT Water Inventory and Analysis Report June 14, 2016 26

Annual Budgets Highlight Changes Over Time Water Inventory and Analysis Report August 23, 2016 27

Valley Floor Inflows/Outflows by Water Year Type Water Inventory and Analysis Report August 3, 2016 28

Water Budget Summary • Irrigated agriculture and wetlands represent the primary use of water and rely mainly on surface water for irrigation • Magnitude of inflows/outflows varies widely by inventory unit (and subinventory unit) and land use category • Annual pumping influenced by precipitation to meet irrigation demands, particularly for orchard crops • Periods of drought result in increased pumping and decreased deep percolation Water Inventory and Analysis Report August 23, 2016 29

Next Steps • Continue to assess the use WI&A information to support development of GSPs under SGMA. • Continue process of updating and calibrating the BBGM. • Further evaluate results to better understand factors contributing to recent historically low groundwater levels in some areas. • Conduct future demands and climate change analysis Water Inventory and Analysis Report August 23, 2016 30

Water Inventory and Analysis Report https: //www. buttecounty. net/wrcdocs/Reports/I&A/2016 WI&AFINAL. pdf Water Inventory and Analysis Report August 23, 2016 31

2016 WI&A Structure 1. 2. 3. 4. 5. 6. 7. 8. Executive Summary Introduction Inventory and Analysis Methodology Land Use and Cropping Patterns Climate and Hydrology • Climate • Surface Water Hydrology • Groundwater Hydrology Historical Water Demands and Supplies Future Water Demands and Supplies Conclusions and Recommendations References Water Inventory and Analysis Report August 23, 2016 32

2016 WI&A Structure (continued) APPENDICES: A. Water Suppliers and Managers B. Butte County Stream Gages and Monitoring Wells C. Subinventory Unit Land Use and Water Budgets D. Assessment of Butte County Drought Impacts, 2012 -2015 Water Inventory and Analysis Report August 23, 2016 33

Acknowledgements • Butte County Board of Supervisors • Davids Engineering, Inc. • Butte County Water Commission and Project Advisory Committee • Local Water Suppliers and Managers, U. C. Cooperative Extension, California Department of Water Resources Water Inventory and Analysis Report August 23, 2016 34

Questions/Discussion Water Inventory and Analysis Report August 23, 2016 35