In an action concerning declaration or partition of rights to water power, the court may appoint a referee and empower the referee to examine into any matters complained of, and upon reasonable notice to the owners or occupants of water power to enter upon and take control of the mills, machinery, flumes, gates, wheels and other appurtenances of such water power and to exercise such reasonable control of the same for such reasonable time and in such reasonable manner as will enable the referee to ascertain the respective rights of the parties and to determine the manner of using, applying and preserving the same.