The Aura River (Finnish Aurajoki; Swedish Aura å) is a river in south-western Finland. Its sources are in the town of Oripää, and it flows through Pöytyä, Aura and Lieto before discharging into the Archipelago Sea in the middle of the city of Turku. The Aura River is brown. The total length of the river is about 70 kilometres (43 mi), and it contains eleven rapids, the biggest of which is Nautelankoski at Lieto. The reserve tap water for Turku Region is drawn from the Aura river, the city's secondary waterworks being situated by the Halinen rapids.
The word "Aura" appears to come from an archaic Swedish word for waterway (aathra, which is still current in the form ådra), but in Finnish it translates as "plow," a name the river lives up to. Situated in an agricultural zone, it is made turbid by surface runoff from nearby farms with eutrophication as the biggest threat. Its condition has been improving since the 1970s and the Aura river is now clean enough to support salmon.
The banks of the river have been inhabited on locations at least 6000 years ago. It is notable for the cultural heritage in Finland. The archdiocese of Finland has been situated near the river since the thirteenth century.