Approval of Conditional Data from the National Water Quality Laboratory Lab Code 9090 -- Low-Level Volatile Organic Chemicals

In Reply Refer to:
Mail Stop 412	
May 1, 2000

Office of Water Quality Technical Memorandum 2000.06

Subject: Approval of Conditional Data from the National Water Quality Laboratory 
         Lab Code 9090 -- Low-Level Volatile Organic Chemicals


It is the policy of the Office of Water Quality (OWQ) that water quality analytical 
data approved by the U.S. Geological Survey (USGS) is produced by laboratories 
approved according to OWQ Technical Memoranda (TM) 98.03 & 2000.02, who are using 
analytical methods approved according to OWQ TM 98.05.  In brief, the methods approval 
process accepts all methods of the US Environmental Protection Agency, ASTM, Standard 
Methods, and methods approved by the USGS.  OWQ TM 98.05 also provides for USGS 
approval of new water quality analytical methods.  


This memorandum announces an exception to the methods and data approval policy of 
the OWQ.  This exception is for the volatile organic chemicals (VOC) method specified 
by the National Water Quality Laboratory (NWQL) Lab Code 9090, which, upon USGS 
approval on October 1, 1996, became Schedule 2020 (Connor,, 1998).  
The exception is that data produced under Lab Code 9090 prior to October 1, 1996 
are now considered to be approved, and can now be reported to the public in data 
bases and be included in data reports.  This exception is based on several factors:  

1.  All data reported using Lab Code 9090 are similar to data produced using 
    Schedule 2020, and all but 8 compounds have data quality identical to that found 
    in the approved Schedule 2020.  These 8 compounds had differing censoring levels 
    applied due to laboratory background concentrations as described in detail in 
    OWQ TM 98.04.  These 8 compounds are:  benzene, ethyl benzene, toluene, xylenes, 
    1,4-dichlorobenzene, methylene chloride, acetone, and carbon disulfide.  

2.  A series of open discussions and data reviews between the National Water Quality 
    Assessment Program (NAWQA), the OWQ, and the NWQL revealed no additional data 
    quality issues with any of the Lab Code 9090 data.
3.  The analytical method did not change throughout the entire period, both before 
    and after October 1, 1996.  


Data produced under NWQL Lab Code 9090 are identified with a Method Code of 'Z'.  
This Method Code shall not be changed so that these data can always be associated 
with Lab Code 9090.  These data have also had their National Water Information System 
(NWIS) District processing Status (DSTAT) set to 'Z' so that these data would not 
be made available to the public.  This DSTAT flag can now be reset to 'R' and the 
data made available as USGS-approved data.  Although these data are correct as 
reported, the different censoring criteria applied to 8 compounds could result 
in misinterpretations unless the guidance provided in OWQ TM 98.04 is followed.  
Please consult that memo for more details.  

In summary, all data produced using Lab Code 9090 are no longer considered conditional.  
They are now approved and can be released and used along with other approved data.  


Connor, Brooke, Rose, Donna L., Noriega, Mary C. Murtagh, Lucinda K., Abney, 
Sonja R. 1998.  Methods of Analysis by the U.S. Geological Survey National Water Quality 
Laboratory-Determination of 86 Volatile Organic Compounds in water by Gas Chromatography/ Mass 
Spectrometry, Including Detections Less Than Reporting Limits.  U.S. Geological Survey, 
Open File Report #97-829, 78 p.

OWQ TM 98.03 - Policy for the Evaluation and Approval of Production Analytical 
    Laboratories ( 

OWQ TM 98.04 - Guidance for Interpretation of NWQL Schedule 2020 and 2021 
    VOC Data (

OWQ TM 98.05 - Policy for the Approval of U.S. Geological Survey (USGS) Water-Quality 
    Analytical Methods (

OWQ TM 2000.02 - Policy for the Reimbursement of Costs for Quality Assurance 
    of Water-Quality Analytical Laboratories ( 

Janice R. Ward
Acting Chief, Office of Water Quality

This memorandum does not supercede any other OWQ Technical Memorandum.

Distribution:	A, B, DC, 
                District and Regional Water Quality Specialists, 
                NAWQA NLT, NAWQA Synthesis Teams, 
                NAWQA Project Leaders, and OWQ Staff