Why Protecting Upstream Watersheds Matters, Insights from the Ayung River

Bali’s Water Begins Elsewhere

Bali’s landscapes are shaped by water.

From the highlands of Kintamani to the southern coastlines, rivers like the Ayung sustain ecosystems, agriculture, and communities across the island. Yet, much of the conversation around water focuses on where it is used, downstream, rather than where it begins.

In reality, the health of these systems starts upstream.

Understanding and protecting these upstream areas is essential, not only for environmental sustainability, but for the long-term resilience of communities that depend on them. This perspective also reflects a growing global emphasis on water stewardship, the responsible use and protection of water resources in a way that is socially equitable, environmentally sustainable, and economically beneficial.

Understanding Watersheds as Connected Systems

A watershed, or Daerah Aliran Sungai (DAS), refers to an area of land where all rainfall flows into a common river system.

This system is interconnected and typically divided into three zones:

1. Upstream (hulu): higher elevation areas where water originates
2. Midstream (tengah): transitional landscapes
3. Downstream (hilir): areas where water accumulates and is widely used

What happens in one part of the watershed directly affects the others. When upstream areas are degraded through deforestation, erosion, or unsustainable land use, the impacts travel downstream in the form of reduced water quality, increased sedimentation, and higher risks of flooding and drought.

Globally, forested watersheds contribute to approximately 75% of accessible freshwater resources (FAO), highlighting the critical role of healthy upstream ecosystems.

Why Upstream Areas Matter

Upstream landscapes function as natural water regulators.

Vegetation in these areas plays several key roles:

• Groundwater recharge: Tree roots allow rainwater to infiltrate the soil, replenishing underground water reserves
• Erosion control: Root systems stabilize soil and reduce sediment runoff into rivers
• Flood mitigation: Slower water absorption reduces sudden downstream flooding
• Water quality protection: Natural filtration improves overall water conditions

When these systems are disrupted, the effects extend far beyond the upstream area itself, impacting entire communities and ecosystems downstream.

The Ayung Watershed: A Critical Lifeline in Bali

The Ayung River is the longest river in Bali, flowing from the highlands of Kintamani to the southern regions.

It supports irrigation systems, community water needs, and local economies along its path. The river also runs near Green School Bali and Green School Foundation, making its health directly relevant to the surrounding ecosystem.

However, increasing pressure from land use changes and environmental degradation, particularly in upstream areas, poses a growing challenge to maintaining this balance.

Farming at the Source: Coffee, Citrus, and Layered Systems

In upstream regions such as Hulu DAS Ayung and Kintamani, farming systems are closely tied to both ecology and economy.

Two of the most important commodities grown in these areas are:

1. Kintamani Coffee (Arabica):

Recognized with a Geographical Indication (GI), Kintamani coffee is known for its distinct citrus notes and is a key export product from Bali. Its cultivation depends on stable microclimates and consistent water availability.

2. Kintamani Citrus (Jeruk Kintamani):

A primary source of income for many farmers, this crop requires balanced soil moisture and is sensitive to environmental changes, particularly water stress and soil degradation.

To sustain these crops, farmers often adopt agroforestry systems that integrate multiple layers of planting:

• Upper layer: avocado trees
• Middle layer: coffee and citrus
• Lower layer: vegetables such as chili and ginger

Within this system, avocado trees play a foundational ecological role.

Their deep root systems help retain water and stabilize soil, directly supporting groundwater recharge and reducing erosion. Their canopy also creates a more stable microclimate, protecting coffee and citrus crops from excessive heat and moisture loss.

Over time, organic matter from these trees enriches the soil, supporting nutrient cycles that benefit the entire farming system.

An Overlooked Reality: Upstream Communities

Despite their importance, upstream communities are often overlooked in environmental interventions.

Support is frequently directed toward downstream areas, where the impacts of water systems are more visible. Meanwhile, farmers in upstream regions, who play a crucial role in maintaining vegetation, protecting water sources, and sustaining ecological balance, receive comparatively less attention.

Because of the interconnected nature of watersheds, interventions in upstream areas can generate multiplied impact, benefiting ecosystems and communities across the entire river system.

A Step Toward Action in Hulu DAS Ayung

On 22 April 2026, in recognition of Earth Day, Green School Foundation carried out a tree planting initiative at Tegal Sari Training Center, located in the upstream area of the Ayung watershed.

The activity included:

1. Planting 40 avocado seedlings (Hass and Red Vietnam varieties)
2. Contributing 250 kilograms of organic compost
3. Involving Agricultural University Scholarship scholars in hands-on learning

The initiative was supported by BWT (Best Water Technology), whose commitment to water stewardship aligns closely with efforts to protect and sustain water systems at their source.

Beyond planting, the activity created space for dialogue with local farmers, offering insight into the realities of working in upstream environments and the challenges they face. While modest in scale, this initiative reflects a broader approach, one that recognizes the importance of upstream action in maintaining long-term water security and ecosystem balance.

Shifting Attention to the Source

Protecting water systems requires a shift in perspective.

It calls for greater attention to upstream areas, where water begins, where ecosystems are shaped, and where interventions can create far-reaching impact.

As environmental pressures continue to grow, strengthening upstream landscapes and supporting the communities who care for them will be essential in ensuring sustainable water systems for the future.

Because every river carries more than water. It carries the health of the land, the work of communities, and the future of everything downstream.

And it all begins at the source.