THE CENTRAL VALLEY (CV) IN CALIFORNIA COVERS APPROXIMATELY 20 000 SQUARE MILES AND IS ONE OF THE MOST PRODUCTIVE AGRICULTURAL REGIONS IN THE WORLD WITH AN ESTIMATED VALUE OF $17 BILLION PER YEAR IN CROPS GROWN. THE REGIONAL POPULATION ALMOST DOUBLED BETWEEN 1980 AND TODAY AND IS PROJECTED TO INCREASE TO 6 MILLION BY 2020. POPULATION GROWTH INCREASED AGRICULTURE PRODUCTION AND MULTI-YEAR DROUGHTS HAVE CREATED AN EXTREME DEMAND FOR WATER. AS A RESULT ~20% OF GROUNDWATER PUMPING IN THE UNITED STATES OCCURS IN THE CV AQUIFER SYSTEM AND SINCE 1960 THE GROUNDWATER STORAGE HAS BEEN DEPLETED BY OVER 70 GIGATONS. THEREFORE IT IS OF CRITICAL IMPORTANCE TO DEVELOP TOOLS AND DATASETS THAT COULD BE USED BY WATER AGENCIES TO MANAGE THE CV AQUIFER SYSTEM WATER RESOURCES AS A WHOLE. ADDITIONALLY THE CV IS IN CLOSE PROXIMITY TO ACTIVE TECTONIC FAULTS: THE SAN ANDREAS FAULT SYSTEM TO THE WEST LESS THAN 30 KM FROM THE VALLEY SIDE THE GARLOCK FAULT ZONE TO THE SOUTH ~10 KM AWAY AND THE EASTERN CALIFORNIA SHEAR ZONE TO THE EAST. RECENT WORKS HAVE DEMONSTRATED THAT LOAD CHANGES ASSOCIATED WITH LOSS OF SURFACE WATER DURING THE 2012-2015 CALIFORNIA DROUGHT LED TO CHANGES IN SEISMICITY ON THE SAN ANDREAS FAULT SYSTEM (AMOS ET AL. 2014) BUT TO THIS DAY NO WORK HAS INVESTIGATED THE LONG-TERM EFFECT FROM THE MULTI DECADAL GROUNDWATER WITHDRAWAL FROM THE AQUIFER SYSTEM HAS HAD IN TERMS OF STRESS CHANGE ON THESE FAULTS. THE PROPOSED PROJECT AIMS TO QUANTIFY THE EFFECT OF THE LAST 25 YEARS OF GROUNDWATER EXTRACTION ON THE STRESS AND SEISMICITY ON THE NEARBY FAULTS AT THE SCALE OF THE CV. THE DRIVING HYPOTHESIS OF THE PROPOSED PROJECT IS THAT THE EFFECTIVE LOAD CHANGES ASSOCIATED WITH LONG-TERM GROUNDWATER WITHDRAWAL ARE LARGE ENOUGH TO INDUCE STRESS CHANGES ON NEARBY FAULTS THAT COULD ALTER THE SEISMIC ACTIVITY. THE GOALS OF THE PROPOSED PROJECT ARE TO 1) CHARACTERIZE 25 YEARS OF SURFACE DEFORMATION ASSOCIATED WITH GROUNDWATER WITHDRAWAL (TWICE AS LONG AS THE CURRENT GPS RECORDS USED TO DESCRIBE REGIONAL DEFORMATION) USING INSAR DATA FROM MULTIPLE SATELLITE PLATFORMS COMBINED WITH EXISTING GPS DATA AND AT THE SCALE OF THE CV; 2) GEODETICALLY CHARACTERIZE THE TIME-DEPENDENT HYDRAULIC PROPERTIES OF THE CV AQUIFER SYSTEM BASED ON THE RELATIONSHIP BETWEEN DEFORMATION AND WATER LEVEL CHANGES; 3) QUANTIFY THE EFFECTIVE LOAD CHANGES DUE TO GROUNDWATER WITHDRAWAL THROUGH DEVELOPMENT OF AN HYDROLOGIC MODEL EXPLAINING THE 25 YEARS OF SUBSIDENCE DATA AND DRAWDOWN OBSERVATIONS AND ACCOUNTING FOR THE TIME-DEPENDENT NON-ELASTIC PROPERTIES; 4) ESTIMATE THE RESULTING STRESS CHANGES ON NEIGHBORING FAULTS; AND 5) EVALUATE THE INFLUENCE OF WATER WITHDRAWAL ON THE SEISMICITY THROUGH ANALYSIS OF THE LONG-TERM SEISMIC CATALOG. THE PROPOSED GEODETIC-HYDROLOGIC APPROACH WILL LEAD TO THE DEVELOPMENT OF TOOLS AND DATASETS THAT CAN BE USED BY WATER MANAGERS TO UNDERSTAND HOW WATER MOVES THROUGH THE AQUIFER SYSTEM AND ADDRESS ISSUES OF SUSTAINABILITY AND WATER COMPETITION. ADDITIONALLY THIS PROJECT WILL ANSWER THE QUESTION OF HOW LONG TERM GROUNDWATER EXTRACTION MAY AFFECT THE STATE OF STRESS ON FAULTS AND THE RESULTING SEISMICITY. THIS PROJECT FOCUSES ON NATURAL HAZARDS AND HUMAN IMPACT TWO OF THE OVERARCHING TOPICS IDENTIFIED IN THE NASA CHALLENGES AND OPPORTUNITIES FOR RESEARCH IN ESI REPORT. IT WILL ADVANCE THE UNDERSTANDING OF THE SOLID EARTH BY CHARACTERIZING HOW GROUNDWATER EXTRACTION MAY INFLUENCE THE EARTHQUAKE CYCLE AND WILL EXPLORES HOW THE SOLID EARTH IS LINKED AND INTERACTS WITH THE BROADER EARTH SYSTEM BY EXAMINING SOLID EARTH AND HYDROLOGIC PROCESSES JOINTLY. FINALLY THIS PROJECT IS RELEVANT TO THE NISAR MISSION AS IT WILL DEMONSTRATE THAT INSAR CAN BE USED TO MONITOR GROUNDWATER RESOURCES AND DEVELOP SUSTAINABILITY PLANS.