On Queensland’s World Heritage-listed K’gari, water is both sacred and abundant. But where does this water come from? How long has it been beneath the ground? And how might climate change affect its future?

These questions are at the heart of a groundbreaking project led by the Butchulla Aboriginal Corporation (BAC), Burnett Mary Regional Group (BMRG), CSIRO, the University of Adelaide, and the Department of the Environment, Tourism, Science and Innovation. Together, this consortium is investigating the hidden lifelines that sustain K’gari’s unique freshwater systems. Using a suite of techniques—from stable isotope analysis and sediment coring to lake bathymetry and water quality sampling—the team is unlocking critical knowledge about the island’s water sources, their age, and their vulnerability.

Why Water Matters on K’gari

K’gari’s perched and window lakes are unlike any in the world. Their quality, colour, and biodiversity are shaped by the delicate interactions between rainfall, groundwater, sand, vegetation, and time. Yet very little is known about their hydrology.

This knowledge gap presents a risk: without understanding where lake water comes from, how long it stays, or how it interacts with groundwater, it is difficult to manage these ecosystems effectively—especially under a changing climate. Already, we’ve seen the consequences: Deepwater Lake, once thought to be buffered by deep aquifers, has dried in recent decades, leading to the local extinction of the endangered honey blue-eye (Pseudomugil mellis)​.

The Butchulla People have long emphasised the importance of caring for water in line with their cultural lore. This project seeks to honour that knowledge by combining Traditional Ecological Knowledge with cutting-edge science to better understand and protect the island’s freshwater resources​.

A Collaborative Approach

The BAC has played a central leadership role in guiding research questions, selecting sampling sites, conducting fieldwork, and shaping the communication of findings. Butchulla Rangers have been trained in sampling techniques, contributing directly to the collection of water from lakes, creeks, rainfall, and groundwater bores across the island.

Sampling has taken place at key sites including Lake Boorangoora (McKenzie), Lake Boomanjin, Lake Garawongera and Deepwater Lake – each representing a different type of lake. These lakes are monitored for a wide array of parameters: stable isotopes (oxygen, hydrogen), tritium, dissolved organic carbon, phytoplankton, turbidity and temperature, and other water quality parameters. Rain gauges and depth loggers have been installed to monitor real-time changes and catch rainfall isotope signatures​.

What Are We Learning?

Through this work, the team is beginning to answer questions that were once unapproachable:

• Are lakes connected to deep or shallow groundwater?
  Stable water isotopes (of oxygen and hydrogen), allow the team to determine whether a lake receives ancient groundwater or is fed primarily by recent rainfall. This distinction affects how resilient a lake is to drought.
• How do lake colours relate to hydrology?
  Lakes with high tannin levels (e.g. Lake Boomanjin) absorb more heat and evaporate faster. The source of these colours may be linked to groundwater inputs or surrounding vegetation.
• What risks does climate change pose?
  Data from sediment cores help infer past lake levels and climate variability. If lakes have dried in the past during wetter-than-now periods, future climate scenarios could present even greater challenges. Real-time water level monitoring also enables early detection of trends in drying or recharge.
• How can this knowledge inform future action?
  The collected data will support climate impact assessments, guide restoration priorities, and improve understanding of ecological health, water source vulnerabilities, and fire preparedness. Ultimately, this will lead to a Butchulla water harvesting decision-making tool for fighting fires that prioritises lake systems based on volume, the environment, and cultural significance.

Looking Ahead

By the end of 2025, the Consortium will have generated a comprehensive dataset covering water quality, lake volumes, isotope ratios, and ecological indicators from 12 lakes and multiple bores on K’gari. This will be one of the most detailed assessments ever undertaken on the island.

But it is only the beginning. The findings will inform future modelling of groundwater and lake systems, assessments of resilience, and restoration planning. Importantly, they will contribute to the global understanding of how sand island ecosystems function—and how they can be protected in a warming world.

As the Butchulla say: Minyang galangoor gu, djaa kalim baya-m — What is good for the land must come first.

Article contributed by the K’gari Water Resource Consortium, which includes the Butchulla Aboriginal Corporation, CSIRO, University of Adelaide, Department of the Environment, Tourism, Science and Innovation, and the Burnett Mary Regional Group.