Inventory of Statewide Brackish Groundwater Resources
M&A uses a GIS-based approach to identify brackish groundwater resources as a future option for meeting statewide water demands.
- Client: Central Arizona Water Conservation District (CAWCD)
- Time frame: 2008–2009
- Location: Arizona (statewide)
In inland areas of the southwestern U.S. and other parts of the world, desalinating groundwater is a feasible option for increasing limited water supplies in response to escalating water demands. "Brackish" water has concentrations of TDS between 1,000–10,000 mg/L — roughly equivalent to an EC of 1,600 to 17,000 uS/cm.
M&A was retained to inventory potential brackish groundwater sources in Arizona that could be used to augment or replace existing CAP supplies. Our services entailed compiling and analyzing data, investigating favorable areas, and reporting on the study findings.
- Prepared a comprehensive database of well construction, water level, and water quality data from publicly available sources
- Organized data to identify areas where brackish groundwater met our minimum criteria for volume and well yield
- Using a GIS platform, prepared statewide maps showing the distribution of EC and TDS values, water level conditions, and the estimated volume of brackish groundwater in storage
- Evaluated data by constructing a matrix of relevant factors for all basins and areas containing brackish groundwater — anticipated well yields, estimated volume of groundwater in storage, depth to groundwater, and estimated lateral and vertical distribution of TDS concentrations
- Reviewed hydrogeologic data and reports and estimated the potential for developing more than 10,000 AF/yr from each brackish groundwater basin / area in a practicable, sustainable manner
- Based on this information and discussions with CAWCD, identified five areas warranting further investigation
- Prepared summary groundwater chemistry tables
- Researched and documented aquifer hydraulic properties
- Identified the sources of, and contributors to, brackish groundwater
- Mapped the lateral and vertical distribution of EC values
- Evaluated the likelihood of changes in land use or water chemistry over time
- Projected potential impacts to existing groundwater users if these brackish sources were developed
We identified five potential areas that could prove favorable for developing brackish water supplies. We also projected the potential impacts to existing groundwater users if these sources were developed.