Gaynor Swamp - exciting results for environmental watering in the Goulburn Wetlands

Brolgas in flight at Gaynor Swamp, by Pat Feehan

In an exciting first for the Goulburn Wetlands, Gaynor Swamp received 1100 megalitres of environmental water as part of the environmental watering program in 2018.

The water, delivered between April and December 2018, resulted in excellent waterbird and vegetation responses.

The outcomes were monitored under the statewide initiative; Victoria’s Wetland Monitoring and Assessment Program (WetMAP) for environmental water.

About Gaynor Swamp

Gaynor Swamp is part of the Corop lakes system near Lake Cooper in the Goulburn catchment. Listed in the ‘Directory of important wetlands in Australia’, Gaynor Swamp is a place of high cultural significance, with Taungurung Land and Water Council holding Registered Aboriginal Party status over the area.

During flooding, Gaynor Swamp receives saline water from Lake Cooper. The resulting saltiness of the local sediments influences the unique food web this wetland supports. Water delivery to Gaynor Swamp is managed by the Goulburn Broken Catchment Management Authority (CMA) in cooperation with Goulburn-Murray Water.

Controlling environmental watering

Simon Casanelia, Environmental Water Manager with Goulburn Broken CMA, says that the timing was right for Gaynor Swamp to be partially filled to maintain the diversity of wetland vegetation, including cane grass, at the site and to provide waterbird breeding and feeding habitat.

“With appropriate infrastructure in place as of February 2018, Goulburn Broken CMA was able to carefully manage environmental water delivery, mimicking more natural wetting and drying patterns of wetlands before they were altered by weirs, dams and channels. Water was released to simulate small floods in autumn and spring with a summer top up, followed by a natural reduction in water levels as temperatures increased into the summer months,” he said.

This video on Goulburn Broken CMA’s YouTube channel shows the water starting to flow as Gaynor Swamp receives its first ever environmental water allocation.

Table 1. Timing, volume and allocation of environmental water delivery to Gaynor Swamp in 2018

The environmental water delivery for Gaynor Swamp was also keenly anticipated by members of the local community.

Prior to the watering, John Avard, Deputy Chair of the Cornella Local Area Planning Implementation Committee said, “this will be great for waterbirds, particularly the brolga... Those of us who live around here really value the wetland and the wildlife it attracts. We're pleased that water for the environment will be used to improve and protect this special spot.”

The results

On cue, wetland flora and fauna responded to the environmental watering. Gaynor Swamp was wet for almost a year, eventually drying in January 2019.  Results were monitored by the Arthur Rylah Institute (ARI) through the WetMAP monitoring program.

Danny Rogers from ARI said the watering regime allowed for a variety of phases.

“During autumn, winter and spring, deep open water was available for ducks such as grey teal, whose numbers peaked in early spring with abundance dropping off as wetland depth receded. During the later stages as shallower water and denser vegetation became prevalent, wading species peaked, including glossy ibis in high numbers for Victorian waterways,” he said.

During November, Mr Rogers noted four brolga pairs exploring the habitat along with 1452 blackwinged stilt, 785 whiskered tern and 107 glossy ibis, however no breeding was recorded.

“Surprisingly, given the nice-looking habitat, abundant macro zooplankton and good numbers of birds, we had no breeding records. We are not sure why, there is much to learn about how to manage environmental water so that it stimulates waterbird breeding,” he said.

Birdlife was not the only beneficiary of the environmental watering. ARI’s November records indicate water was clear and aquatic vegetation was abundant, including striking carpets of red milfoil on the water surface. Vulnerable cane grass stands responded well and aquatic plant growth, flowering, seed set and germination were stimulated. Huge densities of aquatic invertebrates were also observed, providing a feast for those further up the food chain.

More about WetMAP

WetMAP is Victoria’s Wetland Monitoring and Assessment Program for environmental water.

Gaynor Swamp is one of many Victorian wetlands included in the WetMAP monitoring program. Monitoring of wetlands in the Mallee, North Central, Wimmera, Goulburn Broken and Corangamite CMA regions is presently underway or scheduled.

WetMAP aims to measure how the aquatic ecology responds to watering of different frequencies, duration, magnitude and timing, so that environmental water can be used more effectively by waterway managers.

WetMAP has been developed by consultant ecologists, the Department of Environment, Land, Water and Planning (DELWP) Waterway Programs branch and the ARI in collaboration with Catchment Management Authorities and the VEWH.

Monitoring for the current stage of WetMAP (2016–2020) is being coordinated by the ARI.

Through WetMAP monitoring, ARI researchers focus on the effects of water delivery and natural water regimes on vegetation, waterbirds, frogs and fish. Key evaluation questions are developed to examine the short- and medium-term responses of the wetland environment to water management. These questions and hypothesis driven science are considered critical design features of WetMAP.

To expand data collection on waterbirds, WetMAP supports a citizen science monitoring program, led by BirdLife Australia, for gathering additional long-term waterbird data in Victorian wetlands that are not currently monitored through WetMAP.

WetMAP will also involve the development of a Victorian waterbird model using waterbird data from 1980 to present, remotely sensed data and rainfall data. A similar citizen science partnership with Frogs Victoria will supplement frog data collected through the main program.

Gaynor Swamp watchers are enthusiastic about continued environmental water management and monitoring at the site with high hopes of bird breeding events and further positive outcomes for aquatic flora and fauna. The data collected under the WetMAP program in 2018-19 will help to inform the next steps in environmental watering at Gaynor Swamp and across the state.

The WetMAP project is part of the Victorian Government’s $222 million investment over 2016-2020 in improved catchment and waterway health. This investment is a key component of Water for Victoria - the government’s plan for management of our water resources now and into the future.

Read more about WetMAP and the Arthur Rylah Institute

Read more about Goulburn Broken CMA

Read more about Water for Victoria