Onterris, Inc.

The full text of the Principles of Corporate Governance, the Codes of Ethics and Business Conduct and the Charters of the Audit Committee, the Compensation Committee and the Nominating and Corporate Governance Committee are accessible by following the links to “Investors” and “Governance” on the Company’s website atwww.montrose-env.com. The Company will furnish without charge a copy of the foregoing to any person making such a request in writing and stating that he or she is a beneficial owner of common stock of the Company. Requests should be addressed to: Montrose Environmental Group, Inc., 5120 Northshore Drive, North Little Rock, AR 72118, Attention: Investor Relations.