Groundwater accounts for 40 to 60 percent of annual water supply for irrigation

Drought 2014› 6.6 maf surface water

shortage› 5 maf groundwater

pumping increase

Drought 2015› 8.7 maf surface water

shortage› 6.2 maf groundwater

pumping increase

2

Groundwater is the critical margin of adjustment

Sacramento San Joaquin Tulare -6-5-4-3-2-101234

-0.89-0.46

-1.3

2015 Drought Water Supply by Source

Surface Water Groundwater Net Shortage

mill

ion

acre

-fee

t2015 Drought Response

3

Statewide groundwater overdraft

2014 groundwater legislation › AB 1739› AB 1319› SB 1168

SGMA

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21Sacramento San Joaquin Tulare

-4,000,000

-3,000,000

-2,000,000

-1,000,000

0

1,000,000

2,000,000

3,000,000

Cumulative Change in Groundwater Storage, 1999 - 2009

Dry Years Wet Years

Central Valley Region Average Annual Overdraft (acre-feet)

Percent above safe yield

Sacramento 510,000 16% San Joaquin 405,000 18% Tulare 1,475,000 27%

Modeling Drought ImpactsData

Water supplies Crop budgetsTransfers Crop mixGW elevations Other economic parametersEnergy costs Other agronomic/resource infoPumping capacity District and grower surveys

SWAPOutput (economic parameters):•Crop revenues•Acreage•Input use

Physical modelOutput (physical parameters):•Water use•Groundwater pumping•Elevations

GW information

Economically optimal GW pumping

IMPLANOutput:•Employment•Value-added•Output value

Impact summary:Prices, employment, value-added, crop

mix, groundwater pumping, energy costs