THE SUSTAINABILITY OF GROUNDWATER IN TEXAS

Sustainable water supplies are important for meeting the long-term water needs of people and the environment. For many years, Texas planned for the sustainable groundwater resources, even considering the transport of water from the Mississippi River to bring pumping from the Ogallala and other aquifers to sustainable levels. However, with the introduction of regional water planning in 1997, groundwater sustainability has generally not been a focus of planning and management decisions. To assess the sustainability of current use and projected availability, I compiled information on maximum sustainable production to assess the sustainability of the major and minor aquifers in Texas.

Maximum sustainable production amounts to about 4.0 million acre-feet per year while current groundwater production is about 7.1 million acre-feet per year and modeled available groundwater in 2070 (allowable future maximum use) is 8.9 million acre-feet. That means that Texas is currently producing its aquifers 1.8 times the maximum sustainable rate and makes available 2.4 times the sustainable rate. Because the Ogallala Aquifer is such a dominant water supply, I also looked at sustainability of the state’s aquifers with the Ogallala excluded. The maximum sustainable production for the major and minor aquifers of the state without the Ogallala amounts to about 3.3 million acre-feet per year while groundwater production is about 2.6 million acre-feet per year and modeled available groundwater is 6.3 million acre-feet. That means that Texas is currently producing these aquifers (without the Ogallala) 0.8 times the sustainable rate but makes available 1.9 times the sustainable rate. On an aquifer-by-aquifer basis, of the 21 aquifer groups analyzed, 13 are currently being pumped sustainably while 8 are not. Current unsustainable groundwater production ranges from 1.1 times the maximum sustainable production in the Igneous Aquifer to 6.5 times the maximum sustainable production in the Ogallala.