TM94-13 National Water Quality Laboratory Reporting Level for the Oil and Grease in Bottom Material Analysis

The approved method for Oil and Grease in Bottom Material Analysis is published in Techniques of Water-Resources Investigation of the United States Geological Survey, Chapter A3, "Methods for the Determination of Organic Substances in Water and Fluvial Sediments" by Wershaw and others (1987). The method number for the analysis is O-5108-83. This publication states that this method is suitable for dry samples containing at least 1,000 mg/Kg (milligrams per kilogram) of oil and grease. However, the reporting level in the National Water Quality Laboratory (NWQL) Services Catalog is listed as "1 mg/Kg." It is necessary to correct this situation for samples analyzed after October 1, 1994, and conform to the method specifications for a reporting limit of 1,000 mg/Kg. The NWQL sincerely apologizes for any inconvenience caused by this error. The reporting limit in the national database and Schedules, Parameters, and Network (SPN) Program will be changed to <1,000 mg/Kg, effective October 1, 1994. Each District Office should review their data reported prior to October 1, 1994. All data reported as <1 mg/Kg should be changed to <1,000 mg/Kg. All data reported between (and including) 1 mg/Kg and 1,000 mg/Kg should be changed to <1,000 mg/Kg.