Va. Code § 62.1-91
In granting any license the Commission may include in the grant thereof such terms and conditions with respect to the character of construction, operation and maintenance of the proposed dam and works as may be reasonably necessary in the opinion of the Commission in the interest of public safety; and in granting every such license the Commission shall determine what provision, if any, shall be made by the licensee to prevent the unreasonable obstruction of then existing navigation or any unreasonable interference with stream flow. In the case of a dam located across any navigable waters of the United States, the owner shall make such provision for navigation as is required by the Secretary of the Army of the United States.
Va. Code § 62.1-91