The Water for the Environment Monitoring, Evaluating and Reporting (MER) Program measures ecological responses to the delivery of water for the environment. It does this by tracking indicators of river and wetland health across 4 environmental themes:
- river flows and connectivity
- native vegetation
- waterbirds
- frogs.
By monitoring changes in the condition, abundance and distribution of these indicators, we can measure progress towards meeting long-term water plans and Basin Plan objectives. We are also able to continually improve how we deliver water for the environment by increasing our understanding of how river and wetland systems respond to flow and flooding regimes.
Our monitoring efforts focus on wetlands that receive water for the environment, including the Gwydir Wetlands, Macquarie Marshes, Lower Lachlan Wetlands, Lowbidgee Floodplain and the Millewa Forest. We also extended our monitoring efforts to the Narran Lakes.
We measure changes in inundation extent and duration of floodplain wetlands, vegetation condition and extent, and changes in waterbird and frog populations in response to water for the environment.
We use a variety of approaches to determine whether water for the environment is meeting the needs of our river and wetland systems. These include:
- satellite imagery to track inundation and flooding regimes
- depth loggers to understand inundation patterns, including duration
- aerial and ground surveys of waterbird populations
- vegetation mapping using high-resolution imagery
- on-ground surveys of plant species composition
- acoustic recordings and observation to monitor frogs
- environmental DNA to determine the presence of cryptic or threatened species.
We partner with other agencies, including 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.
We also work closely with the Department of Planning and Environment – Water, NSW Department of Primary Industry – Fisheries, and the Murray–Darling Basin Authority (MDBA) through The Living Murray (TLM) program.
We report our findings to the MDBA 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), which is due in 2024.
We provide regular updates to the community through our website and stakeholder engagement.
The year in review
Continuing La Niña conditions and rainfall across the NSW Murray–Darling Basin resulted in widespread areas of inundation. These conditions kept storage levels high and provided full allocations of both planned and held environmental water, allowing water to be delivered to river and wetland habitats. Water for the environment enhanced river and wetland connectivity to support native vegetation, waterbird and frog breeding, native fish migration and recruitment.
River flows and connectivity
In 2022–23, natural river flows inundated extensive areas of floodplain, including critical flood-dependent habitats such as non-woody wetlands, lignum shrublands, as well as the forest and woodland communities of river red gum, coolibah and black box.
We used satellite imagery to measure inundation extents at major wetlands:
- Gwydir wetlands (including Mallowa Creek and Mehi River): almost 279,586 hectares were inundated in total, including 82% (82,280 hectares) of flood-dependent habitat.
- Macquarie Marshes: 248,634 hectares were inundated, including 99% (105,939 hectares) of flood-dependent habitat.
- Lower Lachlan: 345,548 hectares were inundated, including 81% (233,154 hectares) of flood-dependent habitat.
- Lowbidgee floodplain: 241,733 hectares were inundated, including 90% (159,262 hectares) of flood-dependent habitat.
- Millewa Forest: 64,487 hectares were inundated, including 96% (32,428 hectares) of flood-dependent habitat.
This increased the area of habitat availability for waterbirds and frogs and supported wetland vegetation.
Waterbird surveys
Extensive colonial waterbird breeding continued across the NSW Murray–Darling Basin in 2022–23.
A variety of waterbird species bred extensively across major wetland complexes in the Macquarie, Narran, Gwydir, Lachlan, Lowbidgee and mid-Murray. This second ‘bumper’ waterbird breeding season provided a much-needed boost for waterbird populations. Despite this, the long-term Eastern Australian Waterbird Survey continues to demonstrate the ongoing decline of populations across many waterbird species.
For the second consecutive year, colonial waterbird breeding events dominated the waterbird monitoring effort across the department in collaboration with partner agencies and the University of NSW (UNSW). Water levels and water quality were actively managed by environmental water managers to support reproductive success. We used on-ground and aerial methods, undertaken under appropriate scientific and ethics approval, to count nests and species, assess colony health and water levels.
In response to the continuing wet conditions, Narran Lakes, near Brewarrina in north-west NSW, experienced follow-up colonial waterbird breeding after a successful 2021–22 season. Large breeding colonies of straw-necked ibis and pelicans were recorded as well as nesting royal spoonbills, little pied cormorants and Australasian darters.
Natural and managed environmental flows supported 16 species of waterbirds and around 60,000 nests in the Gwydir during the 2022–23 water year.
In the Macquarie Marshes, large numbers of breeding waterbirds congregated, with more than 197,000 colonial waterbird nests counted. We also observed magpie geese in the Gwydir and Macquarie.
In the Lachlan, water for the environment facilitated ideal breeding conditions for pelicans at Lake Brewster. We identified more than 50,000 nests at the lake, making it one of the largest events on record. Monitoring also revealed successful colonial waterbird breeding events across the lower Lachlan.
Wetlands in Gayini supported a large ibis and spoonbill rookery of approximately 100,000 nests. A large pelican breeding event was also supported in the Lowbidgee, with around 28,000 pelican nests reported across the Gayini (Nimmie-Caira) wetlands. Australasian bitterns were heard calling at sites across the Lowbidgee.
A high volume of the endangered Australasian bittern was heard calling in vegetated wetlands in the Barmah–Millewa Forest late in the breeding season. Successful colonial waterbird breeding occurred at other locations in the Barmah–Millewa Forest and Edward–Kolety–Wakool area.
The large numbers of breeding pelicans across NSW saw 1,200 young birds fitted with coloured leg bands, indicating where the pelican had hatched. Orange bands have been attached to juvenile pelicans bred at Lake Brewster in the Lachlan since 2017. In 2021–22, researchers began banding young pelicans with blue bands at the Gayini Wetland in the Lowbidgee. This year, 400 juvenile pelicans received black bands at Narran Lake in north-west NSW. DPE and UNSW researchers are trying to better understand nest-site fidelity, which is the tendency for birds to return each season to the same nesting site. Members of the community are asked to report sightings to support the Lake Brewster pelican banding project and help researchers better understand pelican breeding preferences and hopefully help declining pelican populations.
Intensive monitoring of waterbird breeding colony sites is vital for seasonal adaptive management of environmental water deliveries.
Frog surveys
During the 2022–23 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.
Surveys in the southern NSW Basin indicated that the endangered southern bell frog, one of Australia’s largest frog species, was supported with water for the environment in partnership with local landholders. Our team worked with Saving our Species, CEWH and NSW National Parks and Wildlife Service to deliver water to priority wetlands to support frog breeding over summer.
In the Murrumbidgee, a large number of southern bell frogs were detected at sites around Coleambally and the Lowbidgee. The endangered species was also recorded calling and breeding on private properties in the mid-Murray. Breeding success was also observed in the lower Lachlan where the southern bell frog was recently rediscovered.
Frog surveys in the Northern Basin indicated that flow-dependent frog species such as the spotted marsh frog, eastern sign-bearing froglet, barking marsh frog, Peron’s tree frog, broad-palmed frog and salmon-striped frog, were found across many of our monitoring sites. The number of juveniles identified across the sites indicated frog breeding was widespread over the 2022–23 summer period. We also detected tree-dwelling frogs such as the green tree frog and desert tree frog.
