Proposed San Antonio Groundwater Availability Project Claudia Faunt and Matt Landon California Water Science Center U.S. Geological Survey

Stakeholders Overlying Land Owners Agricultural Interests Los Alamos Community Service District Vandenberg Air Force Base Santa Barbara County Water Agency United States Geological Survey

Benefits of the Study Develop a greater understanding of the hydrology of the San Antonio Groundwater Basin Quantify the resources of aquifer Define groundwater availability with respect to quantity and quality Predict potential effects of continued groundwater overdraft Evaluate impacts of future groundwater development on different parts of the basin under differing climatic and cultural water use scenarios

Objectives (1)refine the geohydrologic framework of the San Antonio Creek Valley, (2)quantify the hydrologic budget of the valley, and (3)develop hydrologic modeling tools to evaluate, analyze, and manage the groundwater resources.

Study Area

Project Tasks (1)data compilation and new data acquisition, Increase groundwater level monitoring network Increase water quality sampling Drill dedicated observation wells Install stream gauges (2) model development, (3) analysis of water availability, and (4) report preparation. Note: Santa Barbara County will be instrumental in the success of these tasks, particularly data acquisition.

Current Hydrologic Data Map showing location of wells, generalized geology, and selected groundwater-level hydrographs.

Multiple-Well Monitoring Sites typical construction

Foothill Road Multiple-Well Monitoring Site Observation Well - Cuyama Example

~40 ft of annual water-level difference Recent Water Levels - Cuyama From USGS Geohydrology Report, 2013

Downward Looking Radar Continuous Stream Gauge: Upper Cuyama River, Ventucopa ( ) Stream Gauge Installation: Reyes Ranch, Santa Barbara Canyon, Ventucopa ( ) Stream Gauges - Cuyama Example Discharge Graphs for Stream Gauges From USGS Geohydrology Report, 2013

MODFLOW with Farm Processes (Schmid and Hanson, 2005) Finite Difference Integrated Hydrologic Model Three dimensional representation of aquifer(s) and zones Simulates recharge, evapotranspiration, flow to wells, flow through different zones I ntegrated Hydrologic and Geohydrologic Model From USGS Geologic Framework Report, 2013

Hydrologic Analysis – Central Valley Example

Hydrologic Analysis – Central Valley Example

Board of Supervisors hearing to approve project: Late summer, 2014 Project kickoff: October, 2014 Existing data compilation: Fall, 2014 Drill dedicated observation wells and auger holes: 2015 Expand water level and water quality monitoring network: Testing of hydraulic properties: Groundwater model development: 2017 Analysis and report, project complete: 2018 Estimated Timeline