The Water for the Environment Program’s monitoring, evaluating and reporting (MER) projects measure ecological outcomes using indicators of river and wetland health across 4 major environmental themes:
- river flows and connectivity
- native vegetation
- waterbirds
- frogs.
By monitoring these indicators and evaluating the outcomes against planned targets, we can measure progress towards meeting long-term water plan objectives and the goals of the Basin Plan. We are also able to continually improve how we deliver water for the environment to meet those objectives by increasing our understanding of how river and wetland systems respond to flow and flooding regimes.
We track changes in the inundation regimes of floodplain wetlands, vegetation condition (plant community composition), and changes in waterbird and frog populations in response to water regimes. Our monitoring efforts focus on wetlands targeted by water for the environment, including the Gwydir Wetlands, Macquarie Marshes, Lower Lachlan Wetlands, Lowbidgee Floodplain and Millewa Forest. We have also extended our monitoring efforts to the Snowy River, in partnership with the Department of Planning and Environment.
A variety of methods are used to monitor environmental indicators including:
- satellite imagery to track floodplain wetland inundation
- aerial and ground surveys of waterbird populations
- on-ground surveys of plant species composition
- acoustic recordings and observation to monitor frogs.
We work with the Commonwealth Environmental Water Holder (CEWH) to collaborate with their MER providers including independent researchers, tertiary institutions, and community groups to improve our understanding through complementary monitoring programs.
Our findings are reported to the Murray–Darling Basin Authority to meet Schedule 12 requirements of the Basin Plan. Schedule 12 includes annual reporting of ecological outcomes at an asset-scale (Matter 9.3) and a 5-yearly evaluation (Matter 8) due in 2024.
We also provide regular updates to the community through our website and stakeholder engagement.
An independent evaluation of our Water for the Environment MER Program between 2014 and 2019 has also been completed.
The year in review
2021–22 was a wet year with widespread rainfall across the NSW Murray–Darling Basin. Increased storage levels enabled water for the environment to be delivered to river and wetland habitats across the state to strategically support river flow connections and inundation of wetlands, native vegetation health, waterbird and frog breeding and native fish health.
River flows and connectivity
In 2021–22 natural river flows inundated extensive areas of floodplain, including critical flood-dependent habitats of non-woody wetlands, shrublands such as lignum, as well as the forest and woodland communities of river red gum, coolibah and black box. This included:
- Gwydir wetlands: (including Mallowa Creek and Mehi River) almost 170,000 hectares were inundated in total including 51% (51,300 hectares (ha)) of flood-dependent habitat.
- Macquarie Marshes: 193,100 hectares were inundated including 93% (99,700 ha) of flood-dependent habitat.
- Lower Lachlan: 98,700 hectares were inundated including 34% (96,700 ha) of flood-dependent habitat.
- Lowbidgee floodplain: 130,200 hectares were inundated including 54% (94,950 ha) of flood-dependent habitat.
- Millewa Forest: 16,500 hectares were inundated including 48% (16,380 ha) of flood-dependent habitat.
The increased area of wetland habitat availability supported waterbird and frog breeding.
Waterbird surveys
Triggered by widespread wet conditions during spring–summer 2021–22, the most extensive colonial waterbird breeding event in more than a decade unfolded across the NSW Murray–Darling Basin.
At least 14 waterbird species established more than 80 individual breeding colonies, with more than 250,000 nests across 6 major wetland complexes in the Macquarie, Narran, Gwydir, Lachlan, Lowbidgee and mid-Murray. The 2021–22 water year was a critical season for breeding, with monitoring by the long-term Eastern Australian Waterbird Survey indicating ongoing decline of populations across many waterbird species.
The extensive colonial waterbird breeding event dominated the waterbird monitoring effort across the department. Water levels were actively managed by environmental water managers to support reproductive success. Colonies were monitored by the department using on-ground and aerial methods under scientific and ethics approvals. We worked with the CEWH, Flow-MER program providers, University of NSW, Local Land Services and private landholders. Monitoring included nest and species counts, colony health and water monitoring.
The Gwydir had its largest breeding event since 2011–12 with 45,000 nests from 14 species supported through to fledging. In Narran Lakes, 10,000 nests were recorded from 12 colonial nesting waterbird species including straw-necked ibis, royal spoonbill, little pied cormorants and Australasian darter.
The Macquarie Marshes saw large-scale waterbird colonies of over 90,000 nests, including 3 ibis colonies of up to 40,000 nests each, as well as several large-scale (5,000+ nests) night heron and egret colonies in river red gum forests.
In the Lachlan more than 30,000 adult pelicans nested at Lake Brewster and successfully reproduced to fledglings, making this the largest breeding event in more than 30 years.
Across the Lowbidgee floodplain more than 20,000 straw-necked ibis and royal spoonbills nested in the Gayini (Nimmie-Caira) wetland system and about 15,000 pelicans nested in Kieeta Lake. Targeted surveys of the endangered Australasian bittern and Australian little bittern were completed in the Lowbidgee during the 2021–22 breeding season, with booming activity concentrated to only a couple of sites.
In the mid-Murray there were about 1,500 colonial waterbird nests.
Intensive monitoring of waterbird breeding colony sites is vital for seasonal adaptive management of environmental water deliveries. Data from this infrequent event contributes to the long-term data record, which is necessary to evaluate our progress towards meeting long-term targets. The aim of these targets is to arrest the decline of waterbirds across the Murray–Darling Basin.
Frog surveys
During the 2021–22 spring-summer, natural inflows and the delivery of water for the environment provided wetland habitat for frogs and supported frog breeding across many monitored sites.
In the Gwydir catchment, 11 frog species were detected including 6 flow-dependent frog species: spotted marsh frogs, eastern sign-bearing froglets, barking marsh frogs, Peron’s tree frogs, broad-palmed frogs, and salmon-striped frogs. Frog breeding was widespread by spring and continued to November for barking marsh and spotted marsh frogs. The wet conditions in November also prompted rain-responding species out of their refuges for breeding. Three burrowing frog species, the striped burrowing frog, knife-footed and water-holding frog, were detected as well as the tree-dwelling green tree frog and desert tree frog.
Surveys in the Macquarie Marshes detected 8 frog species and high levels of frog breeding success. Six flow-dependent species, the spotted marsh frog, barking marsh frog, Eastern sign-bearing froglet, Peron’s tree frog, broad-palmed frog and salmon-striped frog, as well as the tree-dwelling green tree frog and desert tree frog were detected.
The Lower Lachlan was once a refuge for the endangered southern bell frog. The species was detected in 2021 for the first time since 2012. The Saving our Species Team surveyed 21 wetland sites in the lower Lachlan area during the spring of 2021–22 to gain baseline knowledge of southern bell frog distribution in the region. Surveys included the Great Cumbung Swamp region and primarily used acoustic recorders. Southern bell frog numbers appeared to be relatively low at most sites, with the exception of Dry Lake and Lignum Lake. Higher numbers were recorded at sites nearer to the Murrumbidgee region. It’s thought the frogs may have migrated north during wet conditions when parts of the Murrumbidgee River were in flood. Ongoing monitoring will be key to determining the species’ persistence and defining targeted watering strategies.
In the Murrumbidgee Saving our Species staff, in partnership with the CEWH, Coleambally Irrigation and private landholders, conducted surveys for the southern bell frog. Hundreds of southern bell frogs were detected at some sites.
