National Water-Quality Assessment (NAWQA) Program
Changes of dissolved solids (sometimes called total dissolved solids, or TDS) concentrations were evaluated in groundwater samples collected from 1,184 wells in 54 well networks across the United States (Lindsey and Rupert, 2012). Of the 54 well networks that were analyzed for changes in dissolved solids concentrations using the Wilcoxon-Pratt signed-rank test (1959), 22 had statistically significant increases in concentrations of dissolved solids. One well network had a statistically significant decrease in concentrations of dissolved solids.
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