Water resource experts have voiced concern over the lack of sufficient initiatives to maintain environmental flow (e-flow) in rivers and streams before diverting water for hydropower or irrigation.
Environmental flow refers to the volume, timing, and quality of water required to sustain the ecological systems of rivers and streams and support the livelihoods that depend on them. It is not about reverting rivers to their untouched, natural state but striking a balance between water use for human needs—such as energy, irrigation, and drinking water—and preserving broader ecological and societal benefits.
Many rivers and streams connected to hydropower, irrigation, or drinking water projects experience negligible or zero environmental flow, particularly during the winter and dry seasons. This overexploitation of river resources has severely impacted aquatic life and disrupted local farming communities reliant on irrigation.
Experts stress that immediate action is required from all levels of government and local communities to safeguard river health.
Nepal hosts approximately 6,000 rivers and streams, most fed by Himalayan snowmelt, according to the International Water Management Institute (IWMI). While numerous hydropower projects are operational, many more are under construction or in the planning stages. Large-scale irrigation projects are also being developed on major rivers.
Nepal’s hydropower policy, created 23 years ago, requires that all projects maintain at least 10% of a river’s flow for environmental purposes. However, studies reveal that adherence to this rule is rare.
Sections of rivers where water is entirely diverted for hydropower have suffered significant ecological damage. Aquatic life, including fish and other species, has been severely affected, while local farming communities face challenges due to inadequate irrigation facilities or insufficient water flow.
In a workshop organized in Kathmandu by IWMI and the Department of Water Resources and Irrigation, Dr. Dip Narayan Shah, Assistant Professor at Tribhuvan University’s Department of Environmental Science, presented research indicating that around 80% of Nepal’s hydropower projects fail to release the mandated 10% of river flow for environmental purposes.
“We recently studied 50 hydropower centers, and most of them had not released the required water for environmental flow,” Dr. Shah said.
IWMI’s findings highlight that inadequate guidelines, poor enforcement of existing regulations, and insufficient monitoring are the primary reasons for non-compliance with environmental flow mandates.
Nepal currently operates approximately 160 hydropower plants with a total capacity of 3,000 MW. Projects with an additional 10,000 MW of capacity are under construction, while surveys are underway for 8,000 MW more.
Dr. Ram Devi Tachamo Shah, Assistant Professor at Kathmandu University, emphasized that enforcing environmental flow regulations is critical for river health. She advocated for public awareness and training for stakeholders to ensure effective implementation.
Workshop participants, including experts and officials, called for sustainable approaches to hydropower, irrigation, and water supply projects. They emphasized that water use must prioritize the preservation of rivers and their ecosystems.
The proposed Water Resources Bill, currently under parliamentary review, offers hope for addressing environmental flow concerns, they said.
Former Minister for Water Resources, Deepak Gyawali, suggested that localizing river-related projects is the most effective way to ensure sustainability. He underscored the importance of incorporating local communities’ concerns when preparing and implementing Environmental Impact Assessments (EIA).
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