It shall be the duty of the Secretary of the Army to prescribe such rules and regulations in respect to the use and administration of the reservoirs at the headwaters of the Mississippi River as in his judgment the public interest and necessity may require; which rules and regulations shall be posted in some conspicuous place or places for the information of the public. And any person knowingly and willfully violating such rules and regulations shall be liable to a fine not exceeding $500, or imprisonment, not exceeding six months, the same to be enforced by prosecution in any district court of the United States within whose territorial jurisdiction such offense may have been committed. And the Secretary of the Army shall cause such gaugings to be made at or near Saint Paul during the annual operation of said reservoirs as shall determine accurately the discharge at that point, the cost of same to be paid out of the annual appropriation for gauging the waters of the Mississippi River and its tributaries.