Reassessment of the Nation's Saline Groundwater Resources

Declines in the amount of groundwater in storage as a result of groundwater development have led to concerns about the future availability of freshwater to meet drinking water, agricultural, industrial, and environmental needs. Industry and public drinking-water suppliers have increasingly turned to deeper, saline groundwater to supplement or replace the use of freshwater, leading to a 300% increase in the use of saline groundwater between 1995 and 2005. Recent advances in treatment technology have reduced the cost and energy requirements of desalination, making saline groundwater a more viable option for drinking water supplies. Despite the growing demand for alternative water sources, the most recent map showing the occurrence of saline groundwater across the United States was published almost 50 years ago.

The USGS Groundwater Resources Program recognizes the need for a better understanding of saline groundwater resources to support sustainable develop­ment of the resource and to provide reliable science for associated regulatory and policy issues as well as for advancing treatment technologies. To address this need, three pilot studies were conducted (2010-2012) to assess saline groundwater resources at regional scales. The goals of the pilot studies were to determine the availability of data for assessing the distribution and character of saline groundwater and test and develop methodologies for assessing the resource. The recently initiated (2012) National Brackish Groundwater Assessment, which is part of the USGS Water Census, will build upon knowledge gained from the three pilot studies and use a consistent approach across the nation to provide an updated national map of moderately saline, or brackish, groundwater resources less than 3000 feet below land surface, as well as critical information about the physical and chemical properties of the resource.