The said commission may, at any time when the condition of the navigable rivers or when the capacities of all impounding and settling facilities erected by mine owners or such as may be provided by Government authority require same, modify the order granting the privilege to mine by the hydraulic mining process so as to reduce the amount thereof to meet the capacities of the facilities then in use; or, if actually required in order to protect the navigable rivers from damage or in case of failure to pay the tax prescribed by section 683 of this title within thirty days after same becomes due, may revoke same until the further notice of the commission.