EXHIBIT 23.1 ------------ CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS As independent public accountants, we hereby consent to the incorporation by reference in this Current Report on Form 8-K of our report included in the Annual Report on Form 10-K of Columbia Energy Group (File No. 1-1098) for the year ended December 31, 1999. /s/ ARTHUR ANDERSEN LP ------------------------- ARTHUR ANDERSEN LP New York, New York November 1, 2000