case studies:

Fish gates nurture native fish

The Sea to Hume Fishway program was developed to restore fish passage along the Murray River from the Murray Mouth to Hume Dam, a course of over 2225 km.

Fishways are structures placed on or around barriers, such as dams and weirs, to allow fish to move through them. Fishways are used in rivers throughout the Murray-Darling Basin.

Native fish migrate along rivers to breed and find food however dams and weirs along the Murray River prevent fish from moving through the system, leading to a detrimental effect on native fish populations.

The solution has been the implementation of vertical-slot fishway systems. These work by providing a “flow of water” to replicate the natural environment. Section by section, the fishway system mimics slower and faster moving water to allow fish to rest or move quickly through the system to re-join the river beyond the barrier. Rocks and other natural materials are used to provide shelter for smaller fish throughout the fishway system.

The installation of the fishway system in rivers and creeks along the course of the Murray River has increased native fish health and supported the repopulation in areas of depleted fish stocks.

 

 Innovative irrigation

A consortium of Northern Victorian organisations administers federal and state government funding to assist irrigators achieve water savings by improving on-farm irrigation networks. These water savings provide a substantial environmental benefit to the Murray-Darling Basin system.

This $200 million investment program has achieved significant water savings and productivity increases across the regions.

The water savings of 68.1 gigalitres from this region provide a 60 per cent allocation into environmental water into the river system to support river health.

The on-farm irrigation improvements across 58,000 hectares of rural holdings have focused to-date on laser grading, drainage, micro, sprinkler and gravity irrigation systems, channel upgrades and linings, and high tech irrigation scheduling.

Food and fibre production (productivity) per megalitre of water has increased which allows farmers in the region to become more sustainable. And economic health in the region through investment in innovation has led to jobs growth, social cohesion and regional confidence.


Image courtesy Goulburn Broken Catchment Management Authority 2017

Native life to the Campaspe River

The Campaspe River (downstream of Lake Eppalock in Central Victoria) is host to important River Red Gum stands and native fish populations. The high-density of the in-stream wood provides stable habitats for a range of native aquatic fauna.

The platypus, water rat, Murray Cod, Silver Perch, Golden Perch and Murray-Darling Rainbow fish are all important residents to this waterway. Riparian vegetation along the river is vital habitat for the Swift Parrot and the Squirrel Glider.

Together, this river system forms a natural home (ecosystem) for many native species unique to this region.

The connection with the Murray River through the use of water management has allowed this ecosystem to restore and be recolonised by native fish species and flourish with a sustainable native population. Aquatic fauna is being reintroduced into the area through the connectivity of the Campaspe River and the Murray River.

The North Central Catchment Management Authority developed a series of water actions to provide the habitat with the water allocations required for a sustainable ecosystem. This was only possible through the reallocation of water (environmental water) from the Murray-Darling Basin.

The success of this healthy river system has been recorded as:

  • Murray-Darling Rainbow fish were absent from Campaspe river for over eight years. In 2017, these native fish are the most abundant native fish in this river system
  • Silver Perch, another native fish, has begun repopulating with a significant increase in juveniles being recorded
  • Murray Cod are growing in numbers along with the Golden Perch.

Image courtesy North Central Catchment Management Authority 2017


A flourishing Gunbower Forest

Gunbower Forest is a 20 000 hectare flood-dependent forest along the Murray River, downstream of Echuca. An important wetland, it hosts a significant stand of River Red Gums and Australia’s largest inland island – an island recognised internationally by Ramsar Convention (an international treaty for the conservation and sustainable use of wetlands).

The introduction of irrigation to the area in the late 1800s supported the growth of the regional agriculturally providing a mechanism to control the waterways both natural and new. This mechanism to control water led to a variation to the water levels and flow across the seasons – often much higher than was previously naturally occurring. This variation in water flow had ecological impact especially on the native fish population and the health of the River Red Gums.

Environmental water now available in the system has smoothed the variability by filling the gaps in flows caused by irrigation demand within the creek. The more regulated flow supports fish migration and breeding, and promotes enhanced ecosystem function that will build additional benefits such as carbon exchange ensuring a renewed ecosystem.

 The Living Murray structural works program sought to reconfigure the water requirements of the Gunbower Forest through water efficiency. The aim of the program was to structure the water flow so it fed the wetland and floodplain to build sustainable conditions in the forest yet with less water.

Through this program the Gunbower Forest and Creek has seen significant environmental benefits:

  • Healthy feeding, breeding and refuge habitats for waterbirds
  • Water flow that connects the Gunbower Forest to Gunbower Creek to allow fish, insects, crustaceans, molluscs, worms and carbon to move between to support a life cycle of Gunbower’s native fish
  • Maintain populations of small-bodied fish species in forest wetlands and rehabilitate large and small bodied native fish communities
  • Improve the resilience of wetland plant life and help river red gums recover from damage.

Flushes of water delivery in 2016 saw River Red Gums respond with new growth and better health to withstand future dry conditions. A diverse node of aquatic plants has germinated in the wetland including the threatened plant species, the River Swamp Wallaby grass, which has replenished the wetland seedbank across the forest.

Environmental water in autumn and winter supported native fish to connect pools within the creek and all native fish to source food and habitats throughout their growth cycle (from juvenile to adult).

A spring and early summer water flush triggered breeding of Murray Cod which through creek connectivity were able to move from habitat to feed sources along the river system.

The objective this year (2017) is to implement a drying regime of the permanent and semi-permanent wetlands to reduce the number of Carp (an introduced species) across the forest  – Carp numbers have increased significantly in the last two seasons after a large invasion during the natural floods of 2010-2012.


Image courtesy North Central Catchment Management Authority 2017