The river was given its English name in December 1829 by naval ship's surgeon Thomas Braidwood Wilson after his mentor, naval surgeon Alexander Denmark, Physician of the Fleet, Resident Physician at the Royal Hospital Haslar, and past-Physician to the Mediterranean Fleet. Wilson found the river while exploring the area in company of the native Mokare, John Kent (officer in charge of the Commissariat at King George Sound), two convicts and Private William Gough of the 39th Regiment, while his ship Governor Phillips was being repaired at King George Sound.[6][7][8]
A surveyor noted in 1833 that the local Aboriginal people, the Noongar, called the river "Koorrabup" meaning "place of the black swan".[9]
The river flows through Denmark Pipehead Dam. The two tributaries of the river are Scotsdale Brook and Cleerillup Creek.
The southern portion of the river was protected under a management plan of the Shire of Denmark in 2011. The ceremonial site has been used by Noongar people for over 10,000 years as a place of dance, song, marriage preparation, initiation and food gathering.[10] The area has high cultural significance due largely to its totemic significance and creation by the Wagyl in the Dreaming.[11]
Salinity
Historically the Denmark River's water quality declined as a result of land clearing in the catchment area since European settlement. It is estimated that 40% of the river's upper catchment area was cleared and as a result salinity levels increased from 40 mg/L in the 1940s to a peak of 1520 mg/L in 1987 at the Mt Lindesay gauging station.
In 2004 it was announced that salinity levels in the river were decreasing, believed to be the first major river in Australia that had shown a reversal in salinity trends, and that it is possible that the river could provide drinking quality water in the future.[12][13]
By 2012 average annual salinity levels had dropped to 470 mg/L, below World Health Organization guidelines for drinking water for the first time in nearly 40 years. The improved water quality means Denmark Dam has been returned as a drinking water source and back-up water supply for Denmark.[14]
The drop in salinity is mainly attributed to the revegetation of previously cleared farmland with Tasmanian blue gum plantations.[14]
^Wilson, Thomas Braidwood (1833), "Extract of a letter received from Dr J.B. Wilson, R.N., dated King George's Sound, 15th December, 1829", in Cross, Joseph (ed.), Journals of Several Expeditions Made in Western Australia During the Years 1829, 1830, 1831 and 1832: Under the Sanction of the Governor, Sir James Stirling, London: J. Cross, pp. 14–26
^Pearn, John (2001). A Doctor In The Garden: Nomen Medici In Botanicis : Australian Flora And The World Of Medicine. Brisbane, Qld: Amphion Press. p. 136. ISBN978-1864995039.
