ABSTRACT The Edwards (Balcones Fault Zone) Aquifer is a high-yield aquifer that provides water for municipal, military, irrigation, domestic, and livestock uses in south-central Texas, and it discharges to several springs that support groundwater ecosystems. Natural water cycling in the Edwards (Balcones Fault Zone) Aquifer is driven by recharge, which depends on precipitation and runoff over the catchment area and recharge zone of the aquifer. This chapter analyzes the water fluxes in the Edwards (Balcones Fault Zone) Aquifer and how they vary with climatic variability and might vary with modern-age climatic change. This work also evaluates the safe yield of the Edwards (Balcones Fault Zone) Aquifer under historic climatic conditions, which is ~400 thousand acre · feet, or 493 × 10 6 m 3 , annually. These results have implications for aquifer groundwater extraction and human and environmental water requirements, such that future groundwater extraction must be adaptive to precipitation and recharge fluctuations to preserve groundwater ecosystems.