The Parramatta River and Sydney Harbour Bridge: Fact and Fiction

There is often confusion about the river that flows under the Sydney Harbour Bridge. While many believe a river runs beneath it, the truth is that the bridge spans over Sydney Harbour, which is an estuary formed by the confluence of several rivers including the Parramatta River and the Lane Cove River.

Understanding Geo-Geographical Terms

To clarify the confusion, the area through which water flows under the Sydney Harbour Bridge and out to the ocean is actually referred to as a ria. A ria is a drowned valley, typically formed by river erosion and flooded by the sea. While the exact starting point of the ria is uncertain, it is likely to begin near Drummoyne or further upstream of the Parramatta River.

The Sydney Harbour Bridge and its Naming

The Sydney Harbour Bridge is colloquially referred to as “The Sydney Harbour Bridge,” but the name is more than just a nickname. As a child living in Sydney, the author was exposed to the Parramatta River and the Lane Cove River, which both flow into Sydney Harbour, as well as numerous creeks. It is worth noting that while Sydney Harbour is commonly known as such, it is actually known by another name: Port Jackson.

Port Jackson is the real name of Sydney Harbour. Many businesses in Sydney incorporate Port Jackson into their names. For instance, Sydney Harbour is indeed a safe anchorage for a thousand ships, as it was known to early settlers.

Parramatta River: Under the Sydney Harbour Bridge

Interestingly, the Parramatta River runs under the Sydney Harbour Bridge, specifically under the “coat-hangar” Bridge. However, while the river itself does not run under the bridge, the area below it is a tidal estuary with salt water entering from the Pacific Ocean. The Parramatta River flows into this estuary about six kilometers west, near Wentworth Point.

Landscape and Environmental Features

The landscape around the estuary is quite different from a typical riverbed. Wide rounded bays are caused by the tide coming in and going out, while thinner, more channel-like areas to the left are creeks and rivers. River water is typically green or brown, in contrast to the blue color of ocean water.

Historical Context

During the last ice age, when sea levels were much lower, what is now known as Port Jackson was a steep-sided gorge with the Parramatta River flowing through it. As sea levels rose, this gorge was flooded, forming the modern estuary and coastal landscape we see today.

The Parramatta River is the main river flowing into Sydney Harbour. For an event such as the 2000 Olympics, a ferry journey from Circular Quay to Sydney Olympic Park would have involved taking the Parramatta River route.

This article aims to clarify the geographical and environmental aspects of the Parramatta River and Sydney Harbour, helping readers better understand the local geography of Sydney.