Note: Reported working gas volumes for the week ended October 8, 2004 included reclassification of 7 billion cubic feet from working gas to base gas.

Note: This report tracks U.S. natural gas inventories held in underground storage facilities. The weekly stocks generally are the volumes of working gas as of the report date. Changes in reported stock levels reflect all events affecting working gas in storage, including injections, withdrawals, and reclassifications between base and working gas.

Note: The weekly storage estimates are based on a survey sample that does not include all companies that operate underground storage facilities. The sample was selected from the list of storage operators to achieve a target standard error of the estimate of working gas in storage which was no greater than 5 percent for each region. Based on a comparison of weekly estimates and monthly data from May 2002 through July 2004, estimated total working gas stocks have exhibited an average absolute error of 24 billion cubic feet, or 1.1 percent. For an expanded discussion of the relationship between the current and prior estimates, please see Differences Between Monthly and Weekly Working Gas in Storage.