The causeway was once part of the first road to the Illawarra (or Five Islands as it was known then), which was built by the famous Surveyor-General, Sir Thomas Mitchell, between 1841 and 1843. The road crossed the Georges River at the Lugarno-Alfords Point ferry, followed the path of the Old Illawarra Road to Barden Ridge, and then crossed the Woronora River here before continuing up Woronora Road, Engadine. The path can be quite easily followed on a street directory.
The portion of road around the crossing was originally named The Pass of Sabugal by Mitchell, after a town in Portugal where he served in the 95th Rifles during the Napoleonic Wars.
The road was constructed by chain gang convicts, under the supervision of William Darke, after whom Darkes Forest is named.
Unfortunately, the Old Illawarra Road wasn’t one of Mitchell’s finest jobs – steep and difficult – and it was replaced by the road through Tom Ugly’s and Sutherland in 1866.
See the book, “From Bottle Forest to Heathcote” by Patrick Kennedy for all the details.
These days it is a steep fire trail on both sides. It takes 5-10 minutes to get down from Woronora Road at Engadine, but can be a heart-pounding walk back up! Unless the dam wall breaks, the causeway seems to be always very easy to cross, and is a good spot to take ‘walking on water’ photos!
Sources: Immortal Outdoors website
Sharks Forever website