The Emu Plains and Nepean River.

Colonial engraving of Emu Plains.

The first British explorers to visit the area surveyed Emu Plains in August 1790 were led by Watkin Tench, and named it Emu Island, after emus they sighted on the land and in the mistaken belief that the land was actually on an island in the Nepean River. It was first referred to by its current name by Governor Lachlan Macquarie on 15 April 1814, when he toured the island realising that it was not an island but a plain that occasionally flooded giving the appearance of an island.

References:
Ferguson, J. A. Bibliography of Australia Volumes 1-8, Canberra 1976 12842.

Collections:
National Library Australia: Bib ID 2266945
State Library New South Wales: Call Numbers:TQ076098
State Library Victoria: SLT 919.4 C27
State Library South Australia: 919.4 C344