Alluvium developed designs to rehabilitate the existing Beavers Creek weir, provide regulators to enhance flow delivery to Old Man Creek, and provide a vertical slot fishway for fish migration to and from the Murrumbidgee River.

A vertical slot fishway was designed that can cater for variable upstream and downstream water levels of up to 4 metres differential. The fishway has a single entrance and 4 exit gates. The vertical slot design uses sheet piling for the shell structure, and steel baffle plates. This is one of the largest vertical slot fishways in Australia.

The project allows dramatic improvements in flow regime and habitat in the Old Man Creek Anabranch of the Murrumbidgee River.