Michael J Moran/WRD/USGS/DOI 
05/21/2008 03:55 PM	To
William G Wilber/WRD/USGS/DOI@USGS, Wayne W Lapham/WRD/USGS/DOI@USGS, 
Michael C Yurewicz/WRD/USGS/DOI@USGS, Gary L Rowe/DO/USGS/DOI@USGS, John S 
Zogorski/WRD/USGS/DOI@USGS
cc
Michael J Moran/WRD/USGS/DOI@USGS, Terri L Arnold/WRD/USGS/DOI@USGS
bcc

Subject
MTBE trends - update
	
		
		
		Bill and others:
		
		I have been working with Terri Arnold over the last week and we have 
finally made a selection of one-well systems from each principal aquifer 
for detailed analysis.  To summarize, Terri used a simple random selection 
procedure (Jon Scott's program) which selected systems randomly from a PA 
while keeping a minimum separation distance.  It was not possible to use 
Jon's equal-area selection process since the locations of the systems were 
too clustered within each PA to obtain a 30-well selection.  A comparison 
of MTBE detection frequencies in RFG areas for all available systems and 
the selected subset leads me to believe we have a representative subset of 
systems in each PA.  Note that there is a total of 219 systems for 
detailed analysis.
		
		For your info I am attaching an Excel that I consider a master file at 
this point with all of the data and some useful summaries.  Everything is 
in this file including all the MTBE data.
		
		At this point I think we need to decide how to proceed.  I thought I 
remembered that we wanted to contact the first few systems as a group to 
test the responses and fine tune the questionnaire.  I'm not sure if we 
still want to do this or not -- but if we do then we should set a date for 
a conference call soon.  There are several new students here in RC that 
can help with the actual phone calls.
		
		Mike
		
		
		
		
		
		
		
		Michael Moran
National Water-Quality Assessment Program
U.S. Geological Survey
1608 Mountain View Road
Rapid City, SD 57702
(605) 394-3244