The Plumpton Dam at 412-518 Plumpton Road Diggers Rest is significant as a rare, and the second largest known, drystone wall private pastoral dam in Victoria. It is also the second largest of a series of at least four large and medium sized drystone dams built on the former WJT Clarke Rockbank station in the Shire of Melton. The Plumpton Dam on Plumpton Road Diggers Rest isalmost completely intact.
The Plumpton Dam at 412-518 Plumpton Road Diggers Rest is structurally and aesthetically significant at the STATE level. (AHC D2, E1, F1) It is a very substantial and impressive structure, approximately 140 metres long, which continues to operate as a dam. It is a finely constructed bluestone structure, employing an unusual construction technique of 'dry' construction, without mortar. Unlike the similar Rockbank Headstation Dam, all of its stones are roughly worked or squared. Its wall is roughly coursed, each course using similar sized stones. The massive coping stones, of uniform size and well laid, make a significant contribution to the unique aesthetic value of the place. The dam wall contains an angle towards its centre. The earth embankment behind the wall appears to have retained its shape and original form to a unique degree. The excellent integrity and condition of the drystone wall face contribute to the dam's very high aesthetic value, as does its intact rural context. The dam also retains intact return abutment walls at both ends. Together with other similar dams built on the Clarke Rockbank estate, it represents an innovative design solution to local climatic and geographical challenges.
The former Plumpton Dam at 412-518 Plumpton Road Diggers Rest is historically significant at the STATE level. (AHC B2, H1) It is the second-largest of a series of at least four large and medium sized drystone dams to have been built on the Clarkes' Rockbank station in the Shire of Melton. No comparable structure or group of structures, comprising long stone dam walls over wide shallow gullies, is known elsewhere in Victoria. This grand scheme was a local response to the particularly low rainfall of the plains area, the difficulty of sinking 'tank' dams in the shallow bedrock of the area, and the local availability of bluestone. Smaller Melton pastoralists and farmers constructed much smaller and more makeshift dams which were also variations on the same principle.
The dam is also significant for its association with Australia's mid nineteenth century pastoral giant WJT Clarke, and his son Sir WJT Clarke, Victoria's leading citizen in the late nineteenth century, and Australia's first baronet. The dam is expressive of the strategic and inherent importance of the 40,000 acre Rockbank property to the Clarke pastoral empire, especially in relation to the fattening and delivery of sheep for the Newmarket meat trade. The massive structure also conveys a sense of the scale of the Rockbank station, whose domination of the Melton Shire was an increasingly acute grievance to local farmers, culminating in the break-up of the estate in the early twentieth century. It is a major relic of the era of large pastoral estates close to Melbourne.
The dam is also significant for its associations with Australia's first 'Plumpton' greyhound coursing enclosure, built by Sir WJ Clarke immediately adjacent to the dam in 1882-83, from which its name derives; and with Harry Houdini's 1910 flight, one of the claimants to the first powered flights in Australia, which occurred on the same paddock.
Overall, the Plumpton Dam at 412-518 Plumpton Road Diggers Rest is of STATE significance.