Role of the Devils River Watershed in Recharging the Lower Rio Grande

The water budget of the Lower Rio Grande has a complex myriad of water inputs and extractions. For example, approximately 10% of the water that feeds the Lower Rio Grande originates in the Devils River watershed. Recent work suggests that these recharge waters are conveyed over long distances in the Devils River watershed, first as groundwater and eventually as surface water along narrow flow paths that mirror stream and river channels. This hydraulic phenomenon is evidenced by large irrigation wells far upstream in the channel of Devils River. These narrow flow paths allow for efficient extraction by large-capacity wells; however, any water removed from these flow paths by pumping reduces water that would otherwise continue to flow downstream and recharge the Rio Grande. There are potential plans by private and public entities to export groundwater from the Devils River watershed for use elsewhere in urban centers (i.e., San Antonio, San Angelo). It is clear from the hydraulic interdependency described above that removal of water from the Devils River watershed, as either surface water or groundwater, will decrease the amount of water recharged to the Lower Rio Grande by a like amount.