Orion Group Holdings Inc

Evaluation of Disclosure Controls and Procedures

As required, the Company’s management, with the participation of its Chief Executive Officer and Chief Financial Officer, have conducted an evaluation of the effectiveness of the Company’s disclosure controls and procedures (as such term is defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended) as of the end of the period covered by this Quarterly Report on Form 10-Q. Based on that evaluation, the Chief Executive Officer and Chief Financial Officer have concluded that the Company’s disclosure controls and procedures were effective as of March 31, 2026.

Changes in Internal Control over Financial Reporting

We completed the acquisition of J.E. McAmis, Inc. on February 3, 2026. Management’s assessment and conclusion on the effectiveness of our internal control over financial reporting as of March 31, 2026 excludes an assessment of the internal control over financial reporting of J.E. McAmis, Inc. We are in the process of integrating this business, which may result in additions or changes to our internal controls over financial reporting. There were no other changes in our internal control reporting during the three months ended March 31, 2026 that have materially affected, or are reasonably likely to affect, our internal controls over financial reporting.