Murray was barely navigable to shipping. During the later 19th century with the discovery of gold, and the development of sheep and wheat farming along the Murray and its tributaries, the river became a major thoroughfare for the carriage of goods and produce. During the peak period of Murray River commerce (roughly 1855 to 1920) and before the development of rail and road transport, the Murray Mouth with its complex and unpredictable interaction between shallow, shifting and variable currents and the open sea, presented a major impediment to traffic between Adelaide and the Murray settlements, and many vessels foundered or were wrecked there. Water flow River Murray water is used by farmers for irrigation in four of Australia's states, as well as supplying water to most towns along the river, and many further away through various pipelines. It has been widely accepted that too much water is being extracted; however business and political concerns make it difficult to remedy the problem. A visible symptom of the over-extraction of river water is the closing of the Murray Mouth. From October 2002 until 2010 dredging machines operated at the Murray Mouth. Between 2002 and 2006, two machines operated moving sand from the channel to maintain a minimal flow from the sea and into the Coorong's lagoon system. Without the 24-hour dredging, the mouth was at risk of becoming silted and closing, cutting the supply of fresh seawater into the Coorong, which would then warm up, stagnate and die. In mid-2006 the dredging was scaled back as a result of the improved conditions at the mouth. Now only one dredging machine operates, and permission was granted to one commercial operator to navigate the channel between Goolwa and the Coorong, passing the mouth. This operation finished in 2010. Dredging was scheduled to resume in January 2015. Dredging continues at a cost between $3m to $6m annually. Protected area status and other arrangements Australian government The Murray Mouth is immediately adjoined on its northern and eastern sides by the boundary of the Coorong and Lakes Alexandrina and Albert Wetland Ramsar site. South Australian government The Murray Mouth is located within a special purpose area within the Encounter Marine Park and is immediately adjoined on its northern and eastern sides by the boundary of the Coorong National Park. Non-statutory arrangements The Murray Mouth is adjoined on its northern and eastern sides by the boundary of the