In Quest to Save Water, Cape Town Turns Up the Heat On Invasives
Controlled burns are accelerating the fight against thirsty invasive trees while new financing tools are securing the Greater Cape Town Water Fund’s future.
In 2018, a years-long drought pushed Cape Town to the brink of “Day Zero,” the period when the City’s taps were expected to run dry. For the region’s four million residents, the crisis laid bare just how vulnerable water supplies can become in the face of prolonged drought and a changing climate.
Although Cape Town ultimately avoided this worst-case scenario, the experience served as a powerful catalyst for action, prompting renewed investment in solutions that could build resilience to future droughts.
It was then The Nature Conservancy (TNC) helped establish the Greater Cape Town Water Fund (GCTWF) to restore the region’s catchments (or watersheds) and help mitigate future scarcity events. It was a simple yet seemingly counterintuitive water conservation model on its face.
To save water, thousands of trees throughout the catchment had to be cut down.
Typically, tree cover is associated with healthy watersheds. And for good reason. Trees are known for their ability to capture, store and filter rainwater and for their role in replenishing streams and aquifers.
But these weren't just any trees. They were alien invasive pines and eucalyptus, and like many invasive species, these trees spread unfettered throughout the mountainous landscape, soaking up more water than the native vegetation they replaced.
That meant measurably less water was making its way into rivers and dams at a time when the City of Cape Town needed it most. And it meant that native fynbos, of which there are over 9,300 plant species, many found nowhere else on earth, were being choked out.
By clearing invasive trees throughout the catchment and allowing the native fynbos to recover, TNC science estimated the Water Fund could recover up to two months of its yearly water supply. And it could do so at one tenth the unit cost of alternatives like desalination and groundwater exploration.
Eight years on, the Water Fund is delivering on its promise. Today, more than 41,000 hectares (101,270 acres) of invasive trees have been removed throughout the catchment, and follow-up visits have been conducted across the cleared landscape to prevent regrowth of invasives. Those efforts have already helped restore over 37 billion liters (9.5 billion gallons) per year into the streams that fill the region’s dams.
High Stakes
Since its earliest days, the GCTWF has trained and assembled crews of local workers to manually clear invasive trees throughout the catchment, with some even rappelling down mountains to do so. While effective, this approach can be slow and labor-intensive.
To scale its impact, the Water Fund had to move faster. They had to turn up the heat.
While the work to clear trees by hand continues (see "Cliff Hanger"), the team turned to fire to reach locations in the mountains where manual removal is too slow and costly. Controlled burns would allow them to work faster and clear larger areas of the landscape than they previously imagined.
Better yet, it would also give native biodiversity a natural boost. “This is a fire-driven ecosystem,” said Kirsten Watson, who manages the water fund for TNC. “The strategic use of fire through controlled burns and planned follow-up manual treatments doesn’t just reduce invasive plant densities; it can help regenerate native species as well.”
Over the course of nearly two years, a multi-partner coalition led a pioneering effort to integrate controlled burns as a conservation tool throughout the catchment. The forward-looking partners included Cape Town’s Volunteer Wildfire Services (also known as the “flamebusters”), CapeNature, Greater Overberg Fire Protection Association, Overberg District Municipality, Working on Fire and Fynbos Trust.
The partners benefited from knowledge exchanges with water funds around the world facing similar challenges. Through a partnership with New Mexico’s Rio Grande Water Fund in 2025, practitioners shared lessons on using fire as a watershed restoration tool—illustrating the power of a global network to accelerate innovation and strengthen impact.
And while the fire itself grabbed most of the public attention, it was the laborious preparatory work and post-burn conservation work that made the difference.
Take a peek behind the headlines and see what it took for this collaborative team to realize their vision.
Hear TNC's Kirsten Watson explain the fire journey
TNC's Kirsten Watson explains the journey:
When wildfires move across landscapes, they travel fast. But working with fire as a conservation tool is a slow and steady process, taking months of planning to ensure safety and effectiveness.
In the photos and video below, you'll get to explore how The Nature Conservancy, in collaboration with our partners, is using large-scale fire to accelerate the removal of water-thirsty alien pine trees that have spread uncontrollably across the mountain ranges.
This is the first time we are using fire, in addition to manually cutting down invasive trees to restore the landscape. First, you'll see the physically demanding work done by local teams to prepare the target landscape for fire, including the critical step of creating a tracer belt, which acts as a safety line to manage the fire. Then you'll see the sheer power of fire to transform landscapes, from steep mountains overgrown with invasive trees to charred, ash-covered hills overnight.
Fast forward a few months, you'll see a landscape renewed, sprouting native feimbors growing out of the fertile ash. It's all part of a nature-based solution to secure Cape Town's water supply and restore these water catchment areas to their natural state. I am inspired of what we have achieved together and I hope it sparks more large-scale restoration efforts.
Step 1: Prepare for the fire.
Prep Work
Before the first spark, the GCTWF team worked hard to create the perfect conditions for fire. Here, the team is seen cutting grasses and shrubs below ankle-length to create a tracer belt, or fire line, that will help maintain the future blaze.
Step 2: Work with fire . . . on its terms.
In a sudden twist befitting nature's power and unpredictability, a wildfire naturally broke out in the area the team prepped for the controlled burn.
While their plans changed out of necessity, the mission remained the same.
Only thanks to the team’s careful preparation and close collaboration with partners, they were able to act when the fire broke, helping direct the flames to the areas they originally intended for burning.
Step 3: Assess the impact.
When the team returned after the fire, they found a landscape transformed. The fire left behind stands of charred trees, a blanket of ash . . . and if you look closely, new signs of life emerging through it all. Together they monitored the impact of the fire, assessed the number of trees and total area burned and determined their next steps.
Step 4: Monitor the recovery.
Months later, the team returned to see a landscape in the midst of renewal with fynbos in bloom and new life sprouting from the ashes. With the invasive trees gone, seeps, or natural pools of water, were once again seen throughout the landscape, a visible indicator of the project’s success.
Looking Forward
The story of the Greater Cape Town Water Fund is still being written, but its impact is already rippling across the catchment and resonating around the world.
To sustain the Water Fund’s momentum and ensure its future success, long-term investments are needed.
Encouragingly, new financial instruments such as the Cape Water Performance-Based Bond* are beginning to address this challenge. Launched in April 2026, the bond will generate millions in essential funding for the Water Fund and increase the likelihood of a ring-fencing conservation charge to cover future maintenance costs.
With greater financial certainty, initiatives like the Greater Cape Town Water Fund can expand their reach, sustain restoration gains over the long term and deliver lasting benefits for people, nature and local economies.
Editor's Note:
In April 2026, TNC in South Africa announced that it will serve as the implementation agent in the Cape Water Performance-based Bond, a first-of-its-kind financial mechanism issued in collaboration with Rand Merchant Bank (RMB) and FirstRand Bank Ltd (FRB), its parent company. Conservation Alpha serves as an independent design and technical agent, responsible for third-party verification of the environmental results.
The ZAR 2.5B (USD $150M) bond will unlock roughly USD $8M for continued invasives removal, and, if successful, deliver returns for donors and bondholders after five years. The bond is being designed as a blueprint for future projects across South Africa’s catchments, which are facing similar challenges with invasive trees.
“This bond is a blueprint for how innovative, blended finance can help close the global nature finance gap by investing in nature-based solutions that strengthen water security while also unlocking long-term benefits for ecosystems, communities and economies,” said Louise Stafford, country director for TNC in South Africa. “It breaks new ground for investors and conservationists alike, creating a financial model to restore priority catchments across South Africa’s Strategic Water Source Areas (SWSAs) on a sustainable and scalable basis.”
For TNC, the bond also provides a critical lever to engage government and motivate a national policy change that could lay the foundation to scale catchment restoration across South Africa. Learn more.
Related Reading
Landmark Cape Water Performance-based Bond to Support Continued Catchment Restoration in Cape Town, South Africa
The Cape Water Performance-based Bond will enable TNC to continue and scale its catchment restoration work through the Greater Cape Town Water Fund (GCTWF) over the next five years.
Nature-Based Solutions Are Protecting Cape Town’s Water Supply
After five years, the Greater Cape Town Water Fund is returning billions of liters of water to the city and surrounding areas.
Doubling Down on Nature: State of Investment in Nature-based Solutions for Water Security
A new report examines the state of investment in NbS for water security, focusing on understanding whether the growing interest in NbS is translating into more investments on the ground.