Chhukha Hydropower Plant

The Chhukha Hydropower Plant (also spelled Chukha) is a 336-megawatt run-of-river hydroelectric power station located on the Wang Chhu (Raidak River) in Chhukha District, southwestern Bhutan. Commissioned in 1986, it was the first large-scale hydropower project in the country and remains a landmark in Bhutan's economic history. The plant established the bilateral model of Indian-financed hydropower development that has since become the cornerstone of Bhutan's national economy and its relationship with India.^[1]

The project was conceived in the early 1970s during the reign of the Third King, Jigme Dorji Wangchuck, as Bhutan began to modernise and sought revenue sources beyond subsistence agriculture. Construction began in 1974 under an agreement between the Royal Government of Bhutan and the Government of India, with India providing approximately 60 percent of the financing as a grant and the remainder as a soft loan. The project was executed by India's national hydroelectric construction corporation.^[2]

Technical Specifications

The Chhukha plant is a run-of-river scheme, meaning it does not impound a large reservoir but instead diverts water through a diversion dam and channels it through pressure tunnels to an underground powerhouse. The diversion dam on the Wang Chhu is located near the town of Chapcha, while the powerhouse is situated approximately 6 kilometres downstream near Chhukha town. The gross head — the vertical distance the water falls — is approximately 430 metres, one of the highest in the region for a project of this scale.^[3]

The plant houses four generating units of 84 MW each, for a total installed capacity of 336 MW. The design energy output is approximately 1,800 gigawatt-hours (GWh) per year, though actual generation varies with seasonal river flows. The Wang Chhu is fed by glacial melt and monsoon rainfall, producing peak flows during the summer months (June through September) and significantly reduced flows during the dry winter season.

The underground powerhouse was an engineering achievement for its time and location, requiring the excavation of large caverns in the Himalayan rock. Water is conveyed from the intake through a headrace tunnel approximately 6.5 kilometres long, then through steel-lined pressure shafts to the turbines. After generating electricity, the water is returned to the Wang Chhu through a tailrace tunnel.^[4]

Construction and Commissioning

Construction of the Chhukha project began in 1974 and proceeded over more than a decade, reflecting the logistical challenges of building major infrastructure in Bhutan's mountainous terrain during a period when the country had minimal road networks and no domestic engineering capacity for projects of this scale. The project was constructed by India's National Hydroelectric Power Corporation (NHPC), which brought in workers and equipment from India.

The first two generating units were commissioned in 1986, and the remaining two units followed in 1988, bringing the plant to full capacity. The commissioning of Chhukha was a transformative moment for Bhutan. The country went from having negligible electricity generation to becoming a net exporter of power virtually overnight. The project was formally inaugurated in a ceremony attended by senior officials of both countries.^[5]

Economic Impact

The Chhukha plant fundamentally altered Bhutan's economic structure. Before its commissioning, Bhutan's economy was overwhelmingly agricultural, with limited government revenue and heavy dependence on Indian grants for development spending. Electricity exports to India from Chhukha provided the Royal Government with a substantial and reliable revenue stream for the first time, accounting for as much as 45 percent of government revenue in some years during the 1990s.^[6]

The bulk of the electricity generated at Chhukha is exported to India under a bilateral agreement that sets the tariff rate. The tariff has been revised periodically, generally increasing over time. A portion of the power is retained for domestic consumption in Bhutan, contributing to the electrification of nearby towns and districts. The revenues from Chhukha funded Bhutan's early investments in health, education, and road infrastructure, helping the country achieve rapid improvements in human development indicators from the late 1980s onward.

The project also demonstrated the viability of Bhutan's hydropower resources as an economic asset and provided the confidence and institutional experience necessary to pursue larger subsequent projects, including Kurichhu and Tala. The bilateral financing model pioneered at Chhukha — Indian grants and soft loans in exchange for electricity exports at negotiated rates — became the standard template for all subsequent Indo-Bhutanese hydropower ventures.

Operations and Management

The Chhukha Hydropower Corporation Limited (CHPC) was established as a state-owned enterprise to manage the plant's operations. It was one of the first modern corporations in Bhutan and served as a training ground for Bhutanese engineers and managers who would later staff subsequent hydropower projects. Over the decades, the plant has undergone periodic refurbishment and maintenance to sustain its generating capacity.

In 2014, the CHPC was merged with the Bhutan Power Corporation, consolidating the management of Bhutan's domestic power distribution and the Chhukha generation assets under a single entity. The plant continues to operate and export power to India, though its share of Bhutan's total hydropower output has declined as newer, larger plants such as Tala and Mangdechhu have come online.

Environmental and Social Considerations

As a run-of-river project, Chhukha does not create a large reservoir and therefore avoids some of the most severe environmental impacts associated with large dam projects, such as the inundation of extensive land areas and the displacement of large populations. However, the diversion of water does reduce flows in the bypassed stretch of the Wang Chhu, affecting aquatic ecosystems and downstream water users.

The construction phase brought a significant influx of Indian workers into a previously remote area, altering local demographics and social dynamics. Some of the social infrastructure built for the construction workforce, including housing and roads, later benefited the local Bhutanese community. The project area has since become one of the more developed corridors in southwestern Bhutan, partly due to the economic activity generated by the plant.

Legacy

The Chhukha Hydropower Plant holds a foundational place in Bhutan's modern economic history. It proved that the country's vast water resources could be harnessed for revenue generation and national development, setting the stage for the hydropower-led economic strategy that successive Bhutanese governments have pursued. At the same time, the model of Indian-financed development established at Chhukha created a pattern of economic interdependence with India that has had far-reaching implications, including the accumulation of substantial hydropower-related debt that has become a subject of national concern.