Mawsons are proud to have been a part of the Echuca Weir Fishway project (April 2014), providing rocks and stone from our Lake Cooper Quarry.
Rocks of various sizes were laid in 6 rows, stepping down the Campaspe river bed, a structural style often referred to as a ladder or ramp. In most instances, a rock-ramp fishway uses large rocks (or in some cases timbers) to create pools and small falls that mimic natural structures. Because of the length of the channel needed for the ladder, rock ramp fishways are most appropriate for relatively short barriers. They have a good advantage over other styles of fish ladders or elevators in that they also provide fish spawning habitat.
The purpose of the Echuca Weir Fishway was to remove the existing weir and allow fish to move up and down the river freely, thus encouraging breeding, migration and an ultimate increase in native fish numbers.
For more information on this interesting project, you can visit the North Central Catchment Management website or read snippets of the pre-construction information brochure below.
The Echuca Weir on the Campaspe River is being modified to improve fish passage.
The works are being carried out by the North Central Catchment Management Authority (CMA) in partnership with Goulburn-Murray Water (G-MW).
The Echuca Weir was initially constructed in the 1960s as a stream gauging station that required a continuous deep pool of water. Through fish monitoring we now know that the weir inhibits the movement of fish through the area (known as fish passage), especially during low water events.
Restricting fish movement can effectively stop many native fish species from breeding and repopulating waterways by restricting their ability to access breeding partners and spawning grounds. Barriers to fish movement result in long-term flow on effects to the size and sustainability of native fish populations. A healthy native fish population is desirable for both ecological and recreational benefits.
WHAT IS FISH PASSAGE?
Fish passage along waterways is critical to the survival of Australian native fish. Species of both fresh and saltwater fish move within waters at different times to access food and shelter, to avoid predators, and to seek out mates to breed and reproduce. Of the 83 species of freshwater fish in south-eastern Australia, half migrate at least once as part of their life cycle.
Three notable long distance swimmers are the Silver Perch (570 km), Murray Cod (1,000 km) and the Golden Perch which has been recorded swimming a staggering 2,300 km.
In December 2006, the Arthur Rylah Institute for Environmental Research undertook an assessment of barriers to fish movement along the Campaspe River. The Echuca Weir was identified as the highest priority for modification or removal in the Campaspe River.
The structure forms a barrier and its modification will open up 27 km of river for upstream movement of native migratory fish (Golden Perch, Silver Perch and Murray Cod) from the Murray River to the Campaspe Siphon near Rochester.
WHAT WILL THE MODIFICATION WORK INVOLVE?
The current top of the structure (the cap) will be removed to improve fish passage.
In order to complete the works, a temporary coffer dam will be constructed upstream of the weir to hold back water whilst the works are occurring (approximately two weeks).
The coffer dam will be removed when works are completed and the material used to construct it will be reused to stabilise the river bed.