In the 1890s a new mining technology evolved in Victoria using locally designed and built centrifugal gravel pumps to mechanise the established practice of hydraulic sluicing. Promising early results led to a boom in ‘pumped sluicing’ or ‘hydraulic dredging’ to rework old alluvial mining ground on many Victorian goldfields. Although less well known than ‘bucket dredging’ this alternate technology was more widely used, particularly across the central goldfields, with often devastating environmental impacts. From 1890 to 1915, some 2,500 acres of old diggings were reworked by hydraulic dredging producing half a million ounces of gold.

Riding the crest of this boom, a group of Castlemaine, Bendigo, and Ballarat investors acquired 87 acres of ground in 1904 on the northern slopes of Belltopper Hill, and formed the Malmsbury Gold Sluicing Company. Despite a significant investment, the enterprise lasted only five years and never returned a dividend, with its demise reflecting a general trend across the industry. While most former hydraulic dredging sites were later re-landscaped, the ground by Belltopper Hill remained untouched over the following century, allowing a forensic examination of the site, combined with detailed historical research, to provide a unique insight into this little known category of alluvial mining.