A model was created to study how groundwater levels and river flows in the lower San Antonio River Basin in Texas would change with less rain and more pumping. By looking at data from 2006 to 2013, the model showed that reducing recharge by 25% and increasing pumping by 25% could decrease groundwater contributions to the river by 6% to 25%. Some areas would see more groundwater level drops than others during an 8-year drought period with higher pumping.