Much has changed since the Clean Water Act (CWA) was passed in 1972, but not how water quality is regulated. Existing environmental data analyzed with advanced statistical models can bring CWA regulatory compliance into the 21st century. With global warming, and societal concerns about sustainability, modernizing regulatory compliance benefits everyone. The use of maximum concentration limits (MCLs) on individual chemical ions or collections such as total dissolved solids (TDS) applied to all water bodies regardless of type or geographic location is similar to the way medicine was practiced centuries ago when we did not understand human physiology and variability.