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Lake Illawarra's mythical second entrance

 by Mark Jones

 

For some time a persistent rumour has perpetuated that not only does Lake Illawarra have its main entrance next to Windang Island, but a second natural sea entrance apparently “somewhere” along the eastern stretch of the inland waterway.

Even the recent “Lake Wake” rally, roughly aimed at mechanically reopening the lake entrance prematurely, mentioned a mystical second entrance as a possible conduit for fresh seawater. 

Extensive sand extraction of close to 500,000 tons annually at Windang/Primbee around the early 1960s, did in fact allow the sea to breach the formidable Perkins Beach dunes at Kemblawarra.

An 100-foot wide shallow channel made it half-way between the sea and the lake for a short period - although the breach quickly filled with sand again as natural wave and wind action took its course.

To old Lake Illawarra hands it was a loosely-held secret that the second entrance was not in fact that short-lived channel, but the World War II Kemblawarra Tank Trap.

The trap was no natural formation. The authorities of the day mechanically excavated two large adjoining ditches between Perkins Beach and the lake to prevent Japanese tanks and other wheeled vehicles attacking the Port Kembla Steelworks, should the enemy ever land on nearby beaches. 

The Kemblawarra Tank Trap photographed circa 1948: The trap was
excavated during World War II to repel would-be Japanese attacking
forces that might have attempted to sabotage the Port Kembla Steelworks.
Note how the channel runs all the way to the dunes of Perkins Beach. 

Aerial surveillance has long-since shown that besides the natural tributaries running into Lake Illawarra - two of the major western inflows being the freshwater Macquarie Rivulet at Creole Point, and Mullet Creek at Jerretts Point - there is no second sea entrance joining Lake Illawarra.

To the uninitiated eye, particularly if one hadn’t walked over the dunes, the old Kemblawarra Tank Trap with sand built-up along the north-western lakeside bank my well have looked like some type of natural sea channel.

The trap was eventually built over in the 1950s through development at Kemblawarra (the southern ends of King Street and Shellharbour Road cross over the trap today), whereupon stormflows have since flowed through underground pipes to Joes Bay.

Throughout recorded white Australian and passed-down Aboriginal history, Lake Illawarra has been silting and flooding with its entrance being covered by large volumes of ever-shifting sand.

Natural cycles at one point saw the lake entrance not only open, but over nine-feet deep, allowing small sharks and dolphins passage.

The lake even opened on both sides of Windang Island at Perkins and Warilla beaches. But the entrance is forever changing, and remains remarkably unpredictable.

Commercial sand excavation was undertaken along Warilla and Perkins beaches from the 1940s to 1970s. The major sand dune along Warilla Beach, next to today’s beachside car park, was excavated with product even exported to exotic locations such as Waikiki in Hawaii.

The mining allowed the lake entrance at the time to more easily meander its way to the sea, south of Windang Island. Yet, other aerial photographs taken in the 1930s show the lake entrance open to the more commonly accepted entrance at Perkins Beach, to the north of Windang Island.

 

This photograph taken circa 1932 clearly shows the Lake Illawarra entrance
flowing to the ocean south of Windang Island. Note how the Windang Bridge
is yet to be constructed. Yet photos taken in other years during the 1930s show
the entrance flow heading out to the more commonly accepted northern side
of the island at Perkins Beach. 


Joseph Davis wrote in his seminal history volume Lake Illawarra – an Ongoing History:

“The lake may have existed intermittently during an unknown number of interglacial high sea level stands. At these times sand barriers would have formed across the mouth of the local coastal system due to the effects of coastal processes.

“The lake has possessed only one opening to the sea during the entire period of European settlement, but geological experts have reported evidence of very ancient openings (that is during the last ice age 6000 years ago) underneath the sand barrier extending from Warilla towards Port Kembla.”

An even more interesting account of the lake entrance was supplied by Matthew Flinders in 1796 during his famous navigation of the continent in his tiny timber boat, Tom Thumb:

“The entrance appeared to be a small stream which had made a passage through the beach. But we could not tell how it would be possible, even for our small boat, to enter it. We got in with difficulty and rowed up about a mile, up a little more water than the boat drew.

“The boat having touched the ground once or twice, and the rivulet still continuing shoal, we began to relinquish the hope of getting up it. And to consider there might not be enough water to go out again, for the water was scarcely higher than the knees.”

 

ENDS

 

Available photographs:

1/. Circa early 1930s: Lake Illawarra entrance flowing south to Warilla beach. Note Windang Bridge does not yet exist.

2/. Circa 1938: Lake Illawarra entrance flowing to the north, with two main flows joining right at the ocean. Windang Bridge is now apparent.

3/. Circa 1948: The Kemblawarra Tank Trap dug in two stages running from Perkins Beach to the lake. Note the sand lakeside on the north-western bank of the trap. The road is the old Shellharbour Road.

4/. Circa 1960: The Kemblawarra area and Perkins Beach during ongoing massive sand excavation. The larger dark patches on the beach and inland are water bodies, formed by the removal of sand.    

 
Media contacts:

Doug Prosser, LIA chairman, phone 4261 1342

Brian Dooley, LIA executive officer, phone 4224 9633