The masonry arch-walled dam across Hunts Creek was completed in 1856 to supply water for domestic purposes; and was operational until 1909.

[7] On 5 December 2012 the Governor proclaimed Lake Parramatta Reserve as a 'Wildlife Refuge’ under Section 68 of the National Parks and Wildlife Act 1974.

[8] Swimming in Lake Parramatta was permitted between 1920 and 1940; and after a prolonged period of closure due to poor water quality, was reopened to the public in 2015.

[9] The traditional custodians of the land surrounding Lake Parramatta are the Burramatagal and Bidjigal clans of the Darug people, an Aboriginal kinship group of Indigenous Australians.

There is evidence of Aboriginal occupation within the boundaries of Lake Parramatta Reserve in the form of remnant shelters, hand stencils, flaking scars and deposits.

In 1849 a large public meeting of citizens petitioned the Governor for a grant of pounds sterling 3000 ($6000) to provide a wholesome water supply.

The debate over the site continued until the Surveyor General Sir Thomas Mitchell recommended the selection of Hunts Creek.

[7] A new Water Committee changed back to Hunts Creek and had plans prepared by Captain Percy Simpson who was also appointed Engineer of Works.

Before dam construction could begin, it was necessary to cut and shape stones from the quarry and to excavate steps in the abutments to receive each course of masonry.

Plans to reticulate water to the town awaited the granting of appropriate powers to the local authority and the funding of a pump house, filter beds and pipes.

[11][7] During the 1960s there were a number of drowning in the lake - because the water was very warm and muddy at the surface and very cold underneath - causing cramps - in a time when the average person did not swim so well.

[7] The reserve comprises 60 hectares (150 acres) of bush and parkland that is located within 2 kilometres (1.2 mi) of the Parramatta central business district.

Geologically, Lake Parramatta is located on the margins of Wianamatta shale and Hawkesbury sandstone formations, with a resulting variation in vegetation communities.

[7] In detail: Lake Parramatta was listed on the New South Wales State Heritage Register on 23 March 2012 having satisfied the following criteria.

Lake Parramatta Dam is associated with four persons of state significance in the mid to late nineteenth century colony of NSW: Captain Percy Simpson, Edward Orpen Moriarty, Cecil West Darley and William Randle (Randall).

This section of the Great North Road is testament to Simpson's engineering skills and his supervision of convict labour (some working in irons) to a very high standard of construction.

Surveyor General Sir Thomas Mitchell knew of "no other officer in the Colony to whom I could with better expectation as to the results, intrust any work connected with the formation of roads, bridges and streets.".

[17] The challenging road from Lapstone Hill to Mitchell's Pass in the Blue Mountains, bridges at Wollombi, Lansdowne and Duck Creek and the Queens Wharf at Sydney Cove are all attributed to Simpson.

[18][7] About 1849 Moriarty commenced private practice in Sydney as a civil engineer, carrying out various schemes including the development of coal mines at Wollongong; design of the first Pyrmont bridge across Darling Harbour, timber bridges over the Murrumbidgee at Wagga Wagga and the Nepean at Richmond, and supervision of Lake Parramatta Dam.

In October 1858 he was appointed Engineer-in-Chief for Harbours and River Navigation in the Public Works Department which he directed until he retired in December 1888.

Other works included construction and excavation of breakwaters, basins and docks at Wollongong and Kiama; improvements at the mouth of the Clarence and Richmond Rivers; a harbour of refuge at Trial Bay; extensive wharfage in Sydney harbour, and enlargement of the Sutherland Dock at Cockatoo Island Dockyard.

[19][7] William Randle was responsible for construction of the first steam railway in Australia (in Melbourne) and for building Fort Denison (sandstone masonry) in Sydney Harbour.

He built the first railway in NSW from Sydney to Parramatta where he achieved outstanding progress using "modern methods" of shifting spoil in wagons on rails.

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

Lake Parramatta Dam has state significance for its technical innovation and achievement because:[7] "The commencement already made, consists in the formation of a timber frame over the entire site of the dam, running at the height of thirty three feet; along this a travelling-jenny travels, and the operations of raising the blocks and lowering them in their destination are performed with the utmost precision.

The labour is now directed to the excavation of the sides of the ravine to form footings and abutments for the dam wall, and also to preparing and laying the courses.

The circumstances of the water being at its lowest ebb is very propitious to the operations...." Associated with this was a rail line to transport the masonry blocks from the quarry to the gantry at the dam.

The birdlife (mainly waterfowl) and native fauna around the dam and fish in the lake are pleasant distractions from the otherwise drab suburbia of western Sydney.

The amenities include a small beach, barbecues, picnic areas, car parking facilities, a kiosk, and children's playgrounds.

The arch form was maintained, the stones courses were simulated and the original stonework remained in full view, reminiscent of Fort Denison in Sydney Harbour.