A fishway is being incorporated into the Cedar Grove Weir to facilitate the upstream and downstream movement of fish, and its design is similar to fishways used successfully at a number of other weirs in Queensland. The fishway will be about 30 m long by 2 m wide and will vary in height from about 10 m on the upstream side to about 2 m on the downstream side. The structure comprises a downstream holding chamber, a central fishlock and an upstream exit chamber. A system of sensors and valves control the flow rate of the water to ensure that fish are attracted into the fishway. The movement of fish through the structure occurs in a cyclical process, beginning with fish swimming upstream being attracted into the holding chamber. From here, the fish enter the central fishlock through a gate, where the water level rises and the fish are released into the upstream exit chamber, returning to the river. Fish moving downstream can use the fishway in reverse. |