The former Clarke Rockbank station dam at 544-618 Diggers Rest - Coimadai Road, Diggers Rest is significant as a rare and the third largest known drystone wall private pastoral dam in Victoria. It is also the third of the large dams in 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 former Clarke Rockbank station dam at 544-618 Diggers Rest - Coimadai Road, Diggers Rest appears to be substantially intact.
The former Clarke Rockbank station dam at 544-618 Diggers Rest - Coimadai Road, Diggers Rest is structurally and aesthetically significant at the STATE level (AHC D2, E1, F1) as a well constructed and visually impressive structure employing an unusual construction technique. Its random rubble form uses unworked bluestone, characteristically split fieldstone, without mortar, in a style that appears to be essentially based on drystone wall construction techniques, but using large stones. Its wall is roughly coursed, each course using similar sized stones. As with the Rockbank headstation dam, and the Plumpton dam with which it compares most closely, the dam contains an angle towards its centre. Its design is unique and slightly more sophisticated than comparable Clarke dams in incorporating a (lower) rear drystone wall behind its earth wall embankment, and stone-lined overflow channels at both ends of dam. Its intact rural context contributes to the dam's aesthetic. It retains its coping stones, and appears to be of high integrity. 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 Clarke Rockbank station dam at 544-618 Diggers Rest - Coimadai Road, Diggers Rest is historically significant at the STATE level. (AHC B2, H1) It is important as one of the three most substantial examples of the series of at least four large and medium sized dams built by Clarke in the Shire of Melton as part of his Rocklands pastoral property. 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. It 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.
Overall, the former Clarke Rockbank station dam at 544-618 Diggers Rest - Coimadai Road, Diggers Rest is of STATE significance.