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Lower Lakes, Coorong and Murray Mouth

Watering events 2016-17

From summer 2017 environmental water was delivered on the back of high natural flows to the Lower Lakes, Murray Mouth and Coorong.  Approximately 1,200 GL of environmental water from a number of water holders, including return flows from environmental watering events upstream, was coordinated to target continuous barrage flows and fish movement, improve water quality and lower salinity in the Coorong and Lower Lakes.

The continuous barrage releases of above 2GL/day over summer, improved Coorong salinity and provided freshwater releases to attract fish migration through the barrages. An estimated 1.7m native fish across 28 species were observed. The barrages releases also provided suitable conditions in the Coorong South Lagoon for Ruppia growth and recruitment. While conditions were the best for Ruppia growth in more than a decade, filamentous green algae smothered a large portion of the plants before they could set seed.

The Coorong at Lake Alexandrina, where the Murray meets the sea (Goolwa, South Australia).

Ecological objectives

There are 3 high-level ecological objectives for the Lower Lakes, Coorong and Murray Mouth icon site:

  • an open Murray Mouth
  • more frequent estuarine fish recruitment
  • enhanced migratory wader bird habitat in the Lower Lakes and Coorong.

Underpinning these ecological objectives are 16 ecological targets which were developed to quantify changes in the condition of the site. These targets are detailed in the Lower Lakes, Coorong and Murray Mouth Environmental Water Management Plan.

Engagement of the Ngarrindjeri people, Lower Lakes, Coorong and Murray Mouth 

The Ngarrindjeri people work with the South Australian Department of Environment, Water and Natural Resources (DEWNR) on environmental water planning at the Lower Lakes, Coorong and Murray Mouth icon site.

One aspect of the program involves Ngarrindjeri people working together with scientists to capture, measure and identify threatened fish in Lake Alexandrina and Albert. This information is used to monitor the ecological health of the fish and their associated habitat while ensuring cultural needs are maintained.

The joint effort to undertake monitoring has been valuable for Ngarrindjeri participants who have learnt skills in data collection, interpretation and fish ecology. Meanwhile, the DEWNR scientists have been able to learn about Ngarrindjeri culture while working at the icon site.

“We look at numbers, we look at data, we don’t have that real connection that I’ve felt the Ngarrindjeri have. They’ve been able to say, ‘we used to fish here, we used to get swan eggs from here’. I’m very tunnel-visioned, I look at aquatic plants. The insight that’s been passed down through the generations is something that I think a lot of scientists can really learn from, because they [Ngarrindjeri] come at it from the opposite direction, where they look at everything as a whole.” — Dr Jason Nichol, Sub-Program Leader Plant Ecology, SARDI Aquatic Sciences 

Sharing knowledge across cultures also occurs in conversations about environmental watering. The program provides the opportunity for the Ngarrindjeri, DEWNR scientists and the Murray–Darling Basin Authority to get together and talk about where water is needed.

From this collaborative approach, environmental water has been targeted to meet a variety of ecological and cultural objectives. These include providing water to assist fish migration and spawning, providing suitable migratory wader bird habitat, and enhancing germination and recruitment of the vulnerable aquatic plant (Ruppia tuberosa) in the Coorong.

The flowering plant, Ruppia tuberosa is culturally important to the Ngarrindjeri and environmentally important by the DEWNR. Thus South Australia has delivered water aimed at improving the population of flower — an action which met the goals of both groups.

The working relationship between DEWNR and the Ngarrindjeri has grown stronger over the years. This has enabled the Ngarrindjeri to be empowered to lead discussions on how ecological and cultural outcomes can be achieved at their traditional lands and waters.

Past watering events

Water Year Volume (GL)* Outcomes
2015-16 893.8 Frog and native fish recruitment, more than 1,000 nests of colonial waterbirds in the Lower Lakes, and movement of native fish through the barrages.
2014–15 867.1 Managing healthy salinity levels for ruppia, supporting native fresh water and estuarine invertebrates, wetland connectivity and health
2013–14 764.4 Created suitable conditions for flowering and fruiting of ruppia into early summer
2012–13 1090 Maintained connectivity between the lower lakes and estuary, maintained open Murray Mouth, maintained acceptable salinity levels in Lake Alexandrina and provided lateral connectivity with the Murray River channel
2011–12 399.8 Enhanced migratory bird habitat in the Lower Lakes and Coorong, increased frequency of estuarine fish spawning and recruitment and maintained an open Murray Mouth
2010–11 397.3 Enhanced migratory waterbird habitat and allowed greater fish passage across the barrages between the Coorong, Murray Mouth and Lake Alexandrina
2009–10 68.6 Maintained drought refuges for threatened waterbirds and fish species, prevented loss of aquatic vegetation and reduced salinity and the risk of broad scale acidification in Lake Albert

*All environmental water holders