In Reply Refer To:
Mail Stop 412

September 4, 2008

Office of Water Quality Technical Memorandum 2008.06

Subject: Policy for Interpreting and Reporting of Radiological Data

This memorandum establishes and explains the policy of the Office of Water Quality (OWQ) for interpreting and reporting radiological data. Additional details of this policy can be found in the U.S. Geological Survey (USGS) Techniques and Methods, Book 5, Chapter B6, written under contract by consultant Dr. David McCurdy, staff from the National Water Quality Laboratory (NWQL) and the OWQ. Concepts presented are based on nationally recognized standard and guidance references such as MARLAP (Multi-Agency Radiological Laboratory Analytical Protocols), ANSI (American National Standards Institute), and ASTM (American Society for Testing and Materials) as well as several U.S. Environmental Protection Agency documents.

Members of the National Water Information System (NWIS) group and the Phoenix Water-Quality User group were consulted and were instrumental in developing new value-qualifier codes and a remark code for radiological results as listed and described in USGS Techniques and Methods, Book 5, Chapter B6. The new codes will be implemented during 2008.

Background and Purpose

All radiological results obtained through the NWQL’s contract laboratory are reported with complete data packages that includes a narrative, sample information, laboratory information, the result, the Combined Standard Uncertainty (CSU) at 1-sigma, the sample-specific Minimum Detectable Concentration (ssMDC), the contractual a priori MDC, the sample-specific critical level (ssLC), the percent yield, the aliquant size, and results for laboratory quality-control samples. NWQL staff is responsible for evaluating the laboratory data for contract compliance and acceptability of results. The Water Science Centers (WSCs) are responsible for reviewing the results with respect to historical data from the collection site and field quality-assurance sample results. Much of the review by the WSCs is focused on data interpretation.

Unlike typical chemical analysis results for organic and inorganic data, all radiological results are reported with an associated one sigma uncertainty (CSU) and ssLc. It is important, for completeness and scientific accuracy that these two elements are included in data and interpretive reports along with the result. USGS Techniques and Methods, Book 5, Chapter B6, defines and explains these terms, what they mean, and how they are to be used.


It is the intent of the OWQ to establish radiological data reporting policy that will result in consistency throughout the USGS for the interpretation and reporting of radiological data. This policy is detailed in USGS Techniques and Methods, Book 5, Chapter B6.


This policy is applicable to all studies generating radiochemical water-quality data and information under the purview of the OWQ.


McCurdy, D.E., Garbarino, J.R., and Mullin, A.H., 2008, Interpreting and Reporting Radiological Water-Quality Data: U.S. Geological Survey Techniques and Methods, Book 5, Chapter B6, 33 pgs.


Timothy L. Miller /s/
Chief, Office of Water Quality

This memorandum does not supersede any existing policy.

Distribution: All WRD Employees