Molonglo Catchment Rehydration Initiative

Once a vibrant, braided watercourse with rich grasslands, ponds and wetlands, the Molonglo floodplain has suffered under centuries of agricultural and mining pressure. Today, it remains ecologically vital – home to the last known population of the endangered Green and Golden Bell Frog in the region.

Collaboration in Action

The Molonglo Catchment Restoration Initiative (MCRI) was seeded through early support from the NSW Government’s Save Our Species program, recognising the urgent need to protect the last known population of the endangered Green and Golden Bell Frog (GGBF) on the Southern Tablelands and inspired by what was achieved at Mulloon Creek. This foundational funding supported early stage liaison with the landholder and relevant agencies and the development of a recovery and restoration plan for the Carwoola and Foxlow floodplains.

The project has since grown into a deeply collaborative effort involving landholders, the Purves family at Carwoola Station and Edwin and Elizabeth Michell at Foxlow Station, alongside ecologists, water engineers, and scientists, including experts such as Dr Will Osborne and Sam Patmore. Further momentum has been made possible through support from Mulloon Institute, private philanthropy and the NSW Environmental Trust, including two separate $170,000 grants for works and detailed design and regulatory approvals at Carwoola and Foxlow.

In addition, our major sponsor Vitasoy has created an annual campaign, Buy a Litre, Restore a Metre, to build awareness of our work through IGA and Foodland supermarkets, with a percentage of sales going towards regeneration projects such as the MCRI.

Together, this diverse partnership is focused on implementing nature-based solutions to rehydrate the floodplain, rebuild habitat, and secure the future of the GGBF.

Why it matters

The Green and Golden Bell Frog is nationally endangered, and recent monitoring shows that the only known Southern Tablelands population is in severe decline – with no individuals recorded between 2021 and 2024. Urgent habitat intervention is needed to prevent local extinction.

This landscape rehydration initiative is designed to:

• Restore breeding and foraging habitat for the Green and Golden Bell Frog across the Carwoola floodplain, as well as enhance drought refugia along the river.
• Reconnect the river and floodplain to improve water retention, slow erosion and raise water tables.
• Support long-term farm productivity and climate resilience.

“The work Mulloon Institute is undertaking is not only helping create more resilient and productive farms but providing a lifeline for this native frog species.”
– Nichole Overall member for Monaro (Feb 2022 – Mar 2023)

Read the announcement on CityNews
RiotACT coverage
Learn more about the Green and Golden Bell Frog 
Saving Green and Golden Bell Frogs blog post

While at CSS, Water Engineer Prawi Woods achieved acclaim from his peers by winning several awards for his presentation on ‘Rehydrating the Floodplain to Save the Endangered Green and Golden Bell Frog’ at the 2021 Floodplain Management Australia National Conference.

Tim Morrison, an accomplished flood engineer has been working with Mulloon Institute for some years on the MCRI.  In 2022 at the Floodplain Management Australia Conference in Toowoomba, QLD, Tim was awarded best poster for a ‘Weir Optimisation Tool’ he developed that automatically optimises the position of weirs along a river reach to generate the greatest pool volume for the minimum number of weirs.   

Project Stages

Stage 1 – Carwoola

• Covers ~1,100 hectares
• Rehydration of 11 km of river and surrounding floodplain
• Designed to restore wetland function and frog habitat
• Works comprise two components;
  • Eight in-stream structures designed to raise the bed level of the degraded Molonglo River and restore the hydrological function of the Carwoola floodplain.
  • A suite of floodplain interventions to restore connectivity of surface flows between the river and floodplain, including construction of two managed wetlands for Green and Golden Bell Frog habitat.
• Regulatory approvals slowed the project down by two years, but construction of in-stream structures was completed in early 2025 with construction of the floodplain interventions scheduled for August 2025.
• Informed by spatial hydrological modelling from Catchment Simulation Solutions and specialist input from frog experts Dr Will Osbourne and Sam Patmore, and consolidated by Bill McAlister.

Learn more about the Carwoola project

Pictured: Before, during, after of CM8 on the Molonglo River at Carwoola.

Stage 2 – Foxlow

• Covers ~1,200 hectares
• 12 km of river assessed and prioritised for intervention. Detailed design was completed in 2024
• Planning is underway, working towards having regulatory approvals in place by end of 2025
• Due to the scale of the project, implementation will likely occur in stages over a 3-5 year period.

Key proposed works:

• 22 log-sill and rock weir structures to raise the streambed and reconnect flow
• Additional crossing structures to maintain farm access
• Rehydration works on the Yundyguinula Creek

The designs aim to:

• Stabilise eroded banks
• Capture sediment and rebuild streambeds
• Support riparian vegetation
• Rehydrate pastures and moderate microclimates
• Restore and enhance habitat for the Green and Golden Bell Frog across the Molonglo River floodplain

Explore the full Foxlow design blog

Stage 2 underway – June 2025

With construction of Stage 1 works at Carwoola well underway, there is still much to do to implement the full suite of works proposed under the MCRI.

At Carwoola, the focus now moves towards monitoring, including regeneration of vegetation at the intervention sites and along the river corridor and habitat improvements for the Green and Golden Bell Frog. Initial investigations have also commenced for a potential suite of additional in-stream structures within Carwoola, immediately upstream of the recently completed works.

At Foxlow, the immediate focus is finalising project documentation and securing regulatory approvals to be construction-ready by the end of 2025. It is hoped that construction works will commence in 2026 and be completed over a 3-5 year period, subject to funding.

With the benefits of the works now evident at Carwoola, there is also potential for the MCRI to expand beyond the two current properties to encompass other nearby properties within the Upper Molonglo River catchment.

Pictured: Before, during, after of CM1 on the Molonglo River at Carwoola.