Innovative Water Technologies at TWDB June 2012
Faced with dwindling fresh water supplies and an escalating demand for the resource, water planners and managers in Texas are increasingly turning to non-traditional solutions that can create new supplies or better manage existing ones. These solutions include desalinating salty water, treating and reusing waste water, harvesting rainwater, and implementing more efficient storage solutions such as aquifer storage and recovery (a way to store water underground in times of plenty and recover it during times of need). These innovative strategies are projected to collectively provide about 15 percent (approximately 1.3 million acre-feet) of all new water supplies by the year 2060 (2012 State Water Plan).
At the TWDB, the Innovative Water Technologies group gathers and disseminates information on and promotes the use of non-traditional water technologies. Formed in 2005, the group is using legislative appropriations to fund brackish groundwater desalination demonstration projects, seawater pilot plant studies, and rainwater harvesting and water reuse research. The group also manages the Brackish Resources Aquifer Characterization System program, which maps and characterizes the brackish portions of state aquifers, and the Aquifer Storage and Recovery program.
Since 2005, the group has administered contracts for more than a dozen brackish groundwater desalination demonstration projects, and several seawater pilot plant, rainwater harvesting and water reuse studies. Staff also recently completed an exploratory Aquifer Storage and Recovery mapping study for the Corpus Christi Aquifer Storage and Recovery Conservation District and, as part of the Brackish Resources Aquifer Characterization System program, a brackish groundwater study of the Pecos Valley Aquifer in West Texas.
TWDB's efforts are paying off in several areas.
TWDB's financial assistance for pilot plant studies at Laguna Madre Water District and the Brownsville Public Utilities Board has resulted in recommendations for implementing these two full-scale desalination plants. In 2011, voters in the Laguna Madre Water District approved a bond proposition to fund a 1-million-gallon-per-day seawater desalination plant on South Padre Island. The district has not scheduled a start-up date for the project. Across the causeway, the Brownsville Public Utilities Board is planning to build a 2.5-million-gallon-per-day seawater desalination plant, pending resolution of funding issues.
When built, these two desalination plants will guarantee a supply of fresh water to residents who currently rely heavily or entirely on water from the Rio Grande. Over the next 50 years, existing supplies from the river are projected to decline more than 25 percent, making the need for more water supplies particularly critical.
Another ongoing desalination project conducted in coordination with the Texas Commission on Environmental Quality will profoundly impact the permitting of high-pressure membrane systems for treatment of brackish groundwater. Because currently approved methods are expensive, time consuming, and burdensome, the TWDB project will identify alternative ways that municipalities and water utilities can use new membrane systems. Spurred by the ongoing drought, the Texas Commission on Environmental Quality has expressed an interest in adapting (in 2013) at least some of the changes that will be recommended in the TWDB project (draft report planned for late 2012). These changes will help minimize the challenges entities face in pursuing desalination.
Rainwater harvesting is generally considered a building-scale water supply strategy. However, a current study is exploring how to extend that strategy to an entire subdivision. If determined to be feasible, reliance on traditional water supplies, some of which are already under stress, can be reduced. Developers have shown interest in the results of the study, which is scheduled to be completed in fall 2012.
Water produced from innovative solutions represents only a small contribution to overall new water supplies. However, the contribution is important and may likely become even more important as future demand grows and existing supplies decline.