The first major improvements to the river were made between the 1540s and the 1570s, when Arundel became a port, and navigation up to Pallingham was improved, but barges had difficulty negotiating the flash locks that were installed. The work was carried out by Henry FitzAlan, 19th Earl of Arundel, who made the upper section toll-free. Harbour commissioners managed the lower river from Arundel to the sea from 1732, and major improvements to keep the estuary free from silt were sanctioned by an Act of Parliament obtained in 1793. With the coming of the railways and changes in coastal shipping, Littlehampton superseded Arundel as the port of the Arun, and the Littlehampton harbour commissioners are still responsible for the river up to Arundel, collecting tolls for its use.