Authors: Dr Sue Rosen & Dr Sid French

Client: Sydney North Region NSW National Parks and Wildlife Service Ku-ring-gai Chase National Park

We prepared this Statement of Heritage Impact for the demolition of part of the dam wall and the reduction of the pondage of the Brooklyn Dam No. 2. The dam is one of two former railway dams and are heritage items as they are more than 25 years old under the National Parks Act 1977. The dam is also listed as an archaeological site.

It was in association with the construction of the Great Northern Railway that Brooklyn Dam was constructed in 1884. Steam locomotives required large quantities of water and construction of lines necessitated the establishment of reliable water supplies near stations and depots across the state and the country. Dams were an integral aspect of railway infrastructure as rail routes spread to the north, south and west of Sydney. Larger and larger water storages  were needed as train traffic increased and with the introduction of larger water tenders, prolonged drought and variable rainfall meant that dams were typically enlarged across their history or auxiliary or entirely new dams were constructed. The history of the Brooklyn dams is typical of railway dams. Concrete Gravity dams, such as that at Brooklyn rely on their weight to resist water pressure. They are erected on strong rock foundations, and where there is insufficient rock, an embankment will be constructed. Steel cables could be used to anchor the dam to the rock by pre-stressing or post-tensioning.

The introduction of diesel-electric locomotives in 1951 marked the demise of steam trains and it is no coincidence that the electrification of the line to Gosford in 1959 preceded the cessation of the use of the railway dams for railway purposes on 20 January 1960.