Figure 13			
"Trends in the Occurrence of MTBE in Drinking Water Derived from Ground Water in 6 Northeast States, 1993-2006"			

Title:	Detection frequency ofMTBE in drinking water derived from ground water for select one-well public water systems in six Northeast States by year from 1993-2006.		
			
			
Description:	This is a graph of detection frequency of MTBE for one-well systems (n = 150) in all States by year.		
			
			
			
Origin of data:	The data were obtained from the one-well data set on MTBE in drinking water:  150.one.well.systems.selected.by.PA.rdb		
			
			
			
Manipulation of data set:	"Initially, data was made unique by PWSID and SampleYear retaining any quantified concentrations of MTBE.  Then, detection frequencies were computed for all one-well systems in all States by year."		
			
			
			
Other:			
