EXHIBIT 31(a) CEO CERTIFICATION PURSUANT TO RULE 13a-14(a)/15d-14(a) I, Robert E. Evans, certify that: 1. I have reviewed this Quarterly Report on Form 10-Q/A of Peoples Bancorp Inc.; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report; Date: August 14, 2003 /s/ ROBERT E. EVANS ----------------------------------------------- Robert E. Evans Chairman, President and Chief Executive Officer (Principal Executive Officer)