Aboriginal history of the Swan River
To the Whadjuk Noongar traditional owners and custodians, the Swan River, the Derbarl Yerrigan has remained at the heart of their culture and heritage for more than 40,000 years. Aboriginal people cared for the land and its waters as an integral part of their spirit and culture prior to the arrival of Europeans. They would have seen periods of climate change and sea level rises. They lived in harmony with their land and waters, firing the bush, crossing the River, camping along the River banks, getting water from springs, hunting and fishing.
Noel Nannup writes about Boorloo (the Noongar name for Perth) and the Derbarl Yerrigan (the Swan River):
“Boorloo had a series of lakes and big mobs of kwulla, the mullet, would come up from the sea around March to lay their eggs in the shallows where they wouldn’t be disturbed. Also the Swan River, we call it the Derbarl Yerrigan. Now the word derbarl, to my knowledge, means mixing; because it is where you have the sweet water and the salt water coming together, especially near the islands at Burswood. That is where you have got your tidal movement. Water flows under there too…” 
- Nannup, Noel, ‘Caring for Everything’, in Morgan S, Tjalaminu M, Kwaymullina B (eds), Heartsick for Country Stories of Love, Spirit and Creation, WA, 2008, p. 109.