Skip to content

Lindsay, Mulcra and Wallpolla islands cover over 26,100 ha of River Murray floodplain, forming part of the Chowilla floodplain and Lindsay–Wallpolla Island Living Murray icon site that straddles the Victoria and SA border.

The Lindsay, Mulcra and Wallpolla islands floodplain is characterised by a network of permanent waterways small creeks and wetlands. The larger, permanent waterways– Lindsay River, Potterwalkagee Creek and Wallpolla Creek - form the southern boundaries of the site and create large floodplain islands with the River Murray to the north. 

Naturally, these waterways and wetlands would flow and fill in response to high water levels in the River Murray. However, the regulation of the River Murray has reduced its influence on the Lindsay, Mulcra and Wallpolla system. 

Although large floods can still occur, flows through the system are mostly regulated by the River Murray locks 6 to 9. Regulators and containment structures have been built throughout the Lindsay, Mulcra and Wallpolla floodplain and are used to help protect the environmental values at the site.

System map

Environmental watering objectives in Lindsay, Wallpolla and Mulcra

Fish icon
Increase abundance, diversity and movement of native fish
bird icon
Provide feeding and breeding habitat for a range of waterbird species including threatened and migratory species and colonial species (such as the egret)
Fish icon
Provide flows for large-bodied fish (including Murray cod and perch) to swim, feed and breed
Plant icon
Increase the diversity, extent and abundance of wetland plant life

Environmental values

The Mullaroo and Potterwalkagee creeks are renowned for holding large Murray cod. These creeks provide fast flowing fish habitat compared to the nearby weir pools in the River Murray, and large breeding fish in the creeks are an important source of juveniles to the Murray system. The waterways and wetlands throughout the icon site also support several other threatened fish species such as the freshwater catfish, silver perch, Murray–Darling rainbowfish and unspeckled hardyhead. 

The vast scale of the Lindsay, Mulcra and Wallpolla Islands Icon Site is noteworthy because it provides very large expanses of habitat to support wetland-dependent and terrestrial species. When flooded, waterways and wetlands within this system provide excellent habitat for waterbirds, 40 species of which are threatened in Victoria including the great egret and red-necked stint. These formed important criteria in placing Lindsay Island, Lake Wallawalla and Mulcra Island on the Directory of Important Wetlands in Australia. Terrestrial animals also benefit from the improved productivity and food resources when flooding occurs. 

The reduced frequency and duration of floods in the River Murray has degraded the water-dependent vegetation communities, which has in turn caused declines in the diversity and abundance of animals that rely on healthy vegetation for habitat.

Social, cultural and economic values

Lindsay, Mulcra and Wallpolla islands offer recreation opportunities in a remote location with camping, boating and fishing popular for residents of nearby communities and long-distance travellers. 

The wetlands and waterways in the Lindsay, Mulcra and Wallpolla islands system hold significance for Traditional Owners. They are important ceremonial places and for thousands of years have provided resources such as food and materials to the Latji Latji, Wadi Wadi, Dadi Dadi and Wamba Wamba peoples.

Conditions mid-2017

In spring 2016 a major flood in the lower River Murray inundated most of the floodplain across Lindsay, Mulcra and Wallpolla Islands. Floods in the major contributing systems, such as the Edward-Wakool and Murrumbidgee, were the largest in over two decades and washed huge amounts of organic material into the River Murray, causing widespread deoxygenated blackwater and fish deaths. Monitoring has found that although many large fish died, many others found refuge or tolerated the low oxygen and returned to the Lindsay River and Mullaroo Creek when the water quality improved. 

The large overbank flows also improved the condition of important floodplain vegetation. The main observations are increased density of river red gum and black box canopies and improved lignum health.

Scope of environmental watering

Table 1 Potential environmental watering actions and objectives for Lindsay, Wallpolla and Mulcra islands

Potential environmental watering

Environmental objectives

Lindsay Island - Mullaroo Creek

Year-round low flows (up to 600 ML/day)

  • Maintain flowing water habitat for native fish species (such as Murray cod, silver perch and golden perch)

Spring/summer high flow (up to 1,300 ML day for up to 4 months between September and January)1

  • Initiate fish movement and improve spawning and recruitment opportunities for native fish

Lindsay Island – Lindsay River

Year-round low flows (40 ML/day via the northern regulator)

  • Maintain flowing water habitat for native fish species (such as Murray cod, silver perch and golden perch)

Spring/summer high flow (up to 450 ML/day for up to 4 months between September and January via the northern and southern regulator)1

  • Initiate fish movement and improve spawning and recruitment opportunities for native fish

Lindsay Island wetlands

Lake Wallawalla (partial or complete fill in winter/spring)

  • Improve the diversity and condition of littoral zone herbland plants
  • Provide opportunities for waterbird breeding and fledging

Websters Lagoon (partial or complete fill in winter/spring)

  • Maintain wetland habitat for fish and waterbirds

Mulcra Island – Potterwalkagee Creek

Year-round low flows in lower Potterwalkagee Creek (40 ML/day via the Stony Crossing regulator)

  • Maintain flowing water habitat for native fish species (such as Murray cod, silver perch and golden perch)

 

Winter/spring/summer low flows in upper Potterwalkagee Creek (up to 100 ML/day between June and February via the upper Potterwalkagee Creek regulator)

  • Maintain seasonal flowing water habitat for native fish species (such as Murray cod, silver perch and golden perch)

Spring/summer high flows in lower Potterwalkagee Creek (up to 400 ML/day for 3 months between September and January via the Stony Crossing regulator and upper Potterwalkagee Regulator)1

  • Initiate fish movement and improve spawning and recruitment opportunities for native fish

 

Spring/summer high flow in upper Potterwalkagee Creek (up to 150 ML/day for 3 months between September and January)1

Mulcra Island wetlands

Snake Lagoon (partial or complete fill in winter/spring)

  • Improve wetland productivity and habitat for wetland birds and fish

Mulcra Horseshoe (complete fill in winter/spring)

Wetland drying

Wallpolla Horseshoe (partial or complete fill in winter/spring)

  • Maintain variable water levels in the littoral zone to improve wetland productivity

Wallpolla East (partial or complete fill in spring)

  • Improve the condition of the riverine grassy woodland and floodway pond herbland ecological vegetation classes

Sandy Creek (partial or complete fill in spring)

  • Improve the condition of the grassy riverine forest-floodway pond herbland complex ecological vegetation classes

Risk management

In preparing its seasonal watering proposal, Mallee Catchment Management Authority considered and assessed risks and identified mitigating strategies relating to the implementation of environmental watering. Risks and mitigating actions are continually reassessed by program partners throughout the water year.

Engagement

Waterway managers meet communities on environmental watering regionally, although other program partners also play a role.

In each region of Victoria, community engagement on environmental watering happens when environmental watering objectives and priorities are scoped (long term and annually), when delivering environmental water, and when reporting on environmental watering results.

In the Corangamite region communities are involved in decisions about the Moorabool river and Lower Barwon wetlands. This happens through formal advisory groups including a Moorabool stakeholder advisory and the Lower Barwon community advisory committees.

Who is engaged and how

Recreational users

The Mallee Catchment Management Authority meets with recreational users (such as fishers, bushwalkers, various 'Friends of...' groups) on an ad-hoc basis, where recreational users have an opportunity to communicate their priorities and perspectives. A gap in engagement is anglers as there is not an organised representative group.

Parks Victoria is the land manager for many of the sites that receive environmental water. Parks Victoria notifies recreational users about planned environmental water deliveries and communicates the potential impacts of environmental watering (through their website and on-site public signage).

Environment groups

The Catchment Management Authority engages environment groups (such as the Field Naturalists, Landcare and Birdlife Australia) through direct meetings 2-3 times a year. These groups provide advice, communicate their priorities and are keen to understand environmental watering objectives and outcomes. Some groups also provide information on the outcomes of environmental watering (e.g. through bird surveys.)

Landholders/farmers

The Catchment Management Authority engages the Victorian Farmers Federation, and industry groups such as table grape growers, dried fruit growers, citrus growers and landholders with river frontage or private wetlands.

These groups are engaged on environmental water planning (long term and annual scoping) and environmental water delivery. These groups are also engaged on related projects such as the Sustainable Diversion Limit adjustment proposals.

Traditional Owners

There are representatives from multiple Traditional Owner Nations from the Mallee region on the Murray Lower Darling Rivers Indigenous Nations. The Victorian Environmental Water Holder, the Commonwealth Environmental Water Office and the Murray-Darling Basin Association engage the Murray Lower Darling Rivers Indigenous Nations on strategic (often longer term) issues related to environmental watering.

Through the Catchment Management Authority Indigenous facilitator, individual Aboriginal stakeholders and groups are directly engaged throughout the year via the Catchment Management Authority Aboriginal Reference Group.

Councils

The Catchment Management Authority engages with the Mildura and Swan Hill Rural City Councils quarterly. Councils provide advice on potential community impacts of environmental watering and communicate environmental watering information back to the broader community.

General public

The Catchment Management Authority engages and communicates with the general public about environmental watering via SMS, their website, publications and media releases.