Whenever complaint shall be made to the Secretary of the Army that by reason of the placing in any navigable waters of the United States of any bridge pier or abutment, the current of such waters has been so deflected from its natural course as to cause by producing caving of banks or otherwise serious damage or danger to property, it shall be his duty to make inquiry, and if it shall be ascertained that the complaint is well founded, he shall cause the owners or persons operating such bridge to repair such damage or prevent such danger to property by such means as he shall indicate and within such time as he may name, and in default thereof the owners or persons operating such bridge shall be liable in any court of competent jurisdiction to the persons injured in a sum double the amount of said injury: , That nothing herein contained shall be construed so as to affect any rights of action which may have existed prior to .August 11, 18881888-08-11Provided, however