For close to a decade we have helped the Nywaigi Aboriginal people in Tropical North Queensland restore one of their most beautiful and vital wetlands. Mungalla wetlands is adjacent to the Great Barrier Reef and a nursery for fish and wildlife.

The challenge

Wetlands under threat

Mid 2013. Weed infestation above the wall at Mungalla wetlands, Ingham Queensland.

When the Nywaigi people bought Mungalla Station in 1999, they knew their battle to truly reclaim and restore the land was only just beginning. Around one quarter of the 880 hectare station is covered by wetlands, but these wetlands were choked by invasive weeds such as water hyacinth, hymenachne and Aleman grass. The waters were so starved of oxygen that they were nearly barren of fish and bird life.

It wasn't always this way. Older members of the Nywaigi people could recall when the wetlands were so full of life that the sky was black with magpie geese. The wetlands also hold great cultural value to the Nywaigi. However, when Mungalla became a cattle station in the 1940s, an earth wall was built that blocked tidal flows into the wetlands and turned them into freshwater which allowed for ponded pastures for the cattle.

After unsuccessfully tackling the weeds with herbicide, the traditional owners asked CSIRO to help them develop a weed management and water quality plan that would restore the wetlands to their natural state.

Our response

A simple fix has startling results

Mid 2014. One year after wall removal. Native lilies return in large numbers to Mungalla wetlands.

Our study undertook a passive low cost alternative approach to chemical and mechanical weed control using the reinstatement of tidal flows.

For a complex problem, the answer turned out to be remarkably simple: remove the wall and let the salt water do the rest. The removal of the wall (or bund) allowed salt water to enter the wetlands several times a year on high tides. This led to the vegetation in the wetlands returning to a more natural condition, with the disappearance (mortality) of exotic freshwater weeds and ponded pastures, and the reappearance of native vegetation.

The results

An important case study for the Great Barrier Reef

Within just two years of the wall being removed, all the weeds were dead and the wildlife – including a crocodile or two – had returned. Water quality showed marked improvements especially in oxygen content required to sustain aquatic organisms. The number of fish species has continued to increase, and wetland birds (particularly wading species) are returning. This dramatic result is environmentally sustainable.

Early 2016. Mungalla wetlands is clear of weeds. Small bulkuru and water lilies continue to return.

Mungalla Aboriginal Business Corporation that now owns the station have observed that the waters are now home to at least nine species of fish, and serve as nursery grounds for some commercially and recreationally important reef fish such as barramundi and mangrove jack. The corporation conducts regular tours of the wetlands to people from all over the world.

While reinstatement of tidal flow has been successfully applied elsewhere to restore ecological function, the Mungalla study appears to be the first of its kind in the Great Barrier Reef region. It was possibly the first time that a bund had been removed to rehabilitate a wetlands, despite the fact that there are well over a thousand similar barriers up and down the Great Barrier Reef coastline. The case study exemplifies the need for similar restoration efforts to effect reef water quality.

Do business with us to help your organisation thrive

We partner with small and large companies, government and industry in Australia and around the world.

Contact us

Your contact details

First name must be filled in

We'll need to know what you want to contact us about so we can give you an answer.