Proposed San Antonio Groundwater Availability Project

Claudia Faunt and Matt Landon

California Water Science CenterU.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 DataMap showing location of wells, generalized geology, and

selected groundwater-level hydrographs.

Multiple-Well Monitoring

Sitestypical 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 (11136500)

Stream Gauge Installation: Reyes Ranch, Santa Barbara Canyon, Ventucopa (11136600)

Stream Gauges - Cuyama Example

Discharge Graphs for Stream GaugesFrom 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

Integrated 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: 2015 - 2018• Testing of hydraulic properties: 2015-2016• Groundwater model development: 2017• Analysis and report, project complete: 2018

Estimated Timeline