Feasibility of brackish water desalination as an alternative water supply in the Barton Springs/ Edwards Aquifer conservation district

Growing demands for water across the State of Texas has prompted many entities to take into consideration alternative means of obtaining water. The Edwards Aquifer within the Barton Springs/Edwards Aquifer Conservation District (BSEACD) has long been an invaluable and reliable resource in providing high quality water at a low cost. The continued population growth within the BSEACD along with continued drought conditions have strained the resource to the point of having restrictions being placed on production. These restrictions are in response to the potential impact of over-pumping water wells, water quality, springflow, and endangered species. At current permitted pumping, even with all curtailments allowed by statutory authority and current rules, the BSEACD cannot meet Desired Future Conditions during an ongoing drought of record. Within the boundaries of the BSEACD, there exist opportunities for groundwater production in the brackish portion of the Edwards and Trinity aquifers. This paper presents the economic feasibility of undertaking a brackish groundwater desalination project in the saline portion of the Edwards aquifer and also considers technical and regulatory obstacles. It is based upon a model that incorporates prevailing market and hydrogeologic conditions within Central Texas and the BSEACD, such as total dissolved solids content, brackish well depth, concentrate well depth, capital and operational costs of desalination facilities, electricity demands and costs, and water costs into its calculation. Results from this study indicate a reverse osmosis desalination project between the modeled range of 1.25 MGD to 12.5 MGD would be economically feasible. At 2.76 MGD the water would cost $748 per acre foot ($2.30 per 1,000 gal) to produce and gradually decreases in cost as the size of the facility increases due to economics of scale. At approximately 10 MGD of desired daily product generation the optimal price of $648 per acre-foot ($1.99 per 1,000 gal) is reached. While a desalination project within the BSEACD may be economically feasible, there are technical and regulatory obstacles that must be overcome before such project can take commence.