He authorised settlers around the Georges River to take action against Aboriginal raiders and later instructed the military to make pre-emptive strikes.

In 1816 Macquarie issued a call to Aboriginals of the Georges River to lay down arms in return for food, education and secure title to land in the Liverpool area.

Lennox also undertook many other civil engineering works in NSW from 1832 to 1844, when he was appointed superintendent of bridges for the Port Phillip District in Victoria.

Another ironed gang of 50 convicts, together with their military guard, were stationed at a quarry opened by Lennox on the Georges River near Voyager Point (east of present-day Holsworthy).

Lansdowne Bridge was completed and opened by Governor Bourke with great fanfare on 26 January 1836, a testament to the skill of Lennox's design and its convict workforce.

[5] Tegg's Almanac of 1842 concurred in this view that Liverpool Weir had boosted the prosperity of the region, noting that it had brought "abundance...to the door of thousands [and that] cultivation is intended and much waste or inaccessible land has been stamped with an intrinsic and permanent value".

[6][2] The weir at the existing site was a compromise between Lennox's initial suggestions of a dam of wooden piles and puddled clay a short distance upstream of the hospital, and a larger masonry structure 11 miles downstream including a road crossing, lock and swivel bridge.

[2] A wharf was constructed at the weir and boats up to 140 tons displacement carried timber and farm produce to Sydney via Botany Bay.

[8] It noted that the principal wall was ashlar 4 feet (1.2 m) thick, built in a circular form with joints radiating to the upstream side.

Governor Macquarie noted in his journal that Liverpool was "admirably calculated for Trade and Navigation ....where the Depth of Water is sufficient to float Vessels of very considerable Burthen".

The piers of Bunkers Wharf still survived into the living memory of older (former) residents of Liverpool who were alive at the beginning of the twenty-first century.

However, it also shows a derrick crane on the western side, which supports the theory of the downstream end adjacent the left (west) bank being used for cargo handling purposes.

Eventually, decades of flooding caused considerable erosion and the weir needed repairing on several occasions, with a major rebuilding in the 1970s and remediation works in 2007–8.

In 1985 surface flagging on the eastern side was replaced following washout of the core, with cast in-situ 1m square concrete units.

Reportedly, the right abutment had been flood damaged some time after completion and was repaired with dressed sandstone blocks supported on round piles (photographed during the inspection of 1979).

[2] The upstream and downstream masonry walls along with the internal fill provide the mass to resist the water forces and act as a broad beam across the river.

The internal cross walls, while providing only limited structural function would have allowed staged construction in the dry with diversion of the river flows.

The puddle clay rammed between the walls provided the impermeable membrane to create a ponded freshwater storage upstream and prevent the ingress of tidal saltwater.

Typically, a select clay was mixed with sand and an optimum amount of water added to produce a material that was plastic, dense and impermeable when compacted.

[2] In the combined report of the state of the weir dated 21 September /1857, Joseph Brady of the Railway Department and James Moore of the Colonial Architect's Department ascertained that in 1851 an addition was made to the Dam on the upper side by driving a double row of timber piles about 13 feet (4.0 m) lengths, 13 feet (4.0 m) from the back (stone upstream) wall ... driven into the silt at the back of the dam but they did not reach the bed of the river.

Both the row of piles and 1836 sandstone back wall were uncovered during the 2008 works including numerous pairs of one metre long wrought iron bars.

The bars were anchored into the top of the sandstone wall with lead and with the free end threaded, complete with square nut.

[2] The repairs to address flood damage would also have prompted the authorities, as part of the works, to increase the storage of the weir by raising it and to provide dry access across the river.

[2] The puddle clay fill within the weir had been exposed, washed out, and replaced and disturbed by repairs including dwarf concrete cut-off walls.

At the time the weir was damaged by the November 2007 flood and remediation works were carried out in 2008, the puddle clay was no longer an original element.

The piping failure of the clay core and the subsequent sinking and washout of the flag units required installation of a free draining layer of railway ballast wrapped in geotextile.

The clay core was suffering a network of piping failure and causing the concrete flag units to settle and dislocate under flood conditions.

It demonstrates the harsher punishment regime in NSW decreed by the British Government from the mid 1820s to the 1840s in order to revive the fear and dread of transportation.

[2] The weir is a rare surviving example of early colonial engineering and demonstrates some of the difficulties overcome in designing water related infrastructure at this time.

[2] The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales.