Uma Oya Hydropower Complex

The Uma Oya Hydropower Complex — formally known as the Uma Oya Multipurpose Development Project (UOMDP) — is one of Sri Lanka's most ambitious water resource and energy infrastructure projects. Located in the Badulla District of the Uva Province, the scheme harnesses the hydrology of the Uma Oya river basin to generate electricity and deliver irrigation water to tens of thousands of hectares of agricultural land. From its early planning stages in 1989 to its official inauguration in April 2024, the project represents more than three decades of engineering ambition and political complexity.

What is the Uma Oya Hydropower Complex?

At its core, the UOMDP is a cross-basin water transfer scheme: it captures water from two tributaries of the Uma Oya — Dalgolla Oya and Mathatilla Oya — and routes it through a network of dams, tunnels, and a purpose-built underground power station before releasing the water onto the dry lowlands to the east for agriculture.

The scheme involves two primary dams. A dam on Dalgolla Oya directs water through a 3,975 m headrace tunnel to Mathatilla Oya, where a second dam forms the main reservoir. From there, approximately 145,000,000 m³ of water per year travels through a 15,290 m headrace tunnel to the Uma Oya Power Station, which sits underground in a cavern excavated from around 68,000 m³ of earth. After passing through the turbines, the water exits via a 3,335 m tailrace tunnel into the Alikota Aru, where it is distributed for agricultural use.

How does the Uma Oya Power Station work?

The Uma Oya Power Station is an underground facility housing two Pelton turbine generators, each rated at 60 megawatts, giving the station a combined installed capacity of 120 MW. Water reaches the turbines via a 600 m vertical pressure shaft, converting the kinetic energy of the steep descent into electricity. The plant is designed to generate up to 231 GWh of electricity per year — enough to make a meaningful contribution to Sri Lanka's national grid.

Power from the station is stepped up at a 5,000 m² switchyard located at around 504 m above mean sea level. From there, it travels over 21.5 km of double-circuit 132 kV transmission line — supported by more than 70 towers — to the Badulla Substation, which feeds the island's Southern Grid.

What are the irrigation benefits of the project?

Beyond electricity generation, the UOMDP was designed to address chronic water scarcity in Sri Lanka's dry zone. The annual discharge from the power station is channelled for agricultural use across approximately 15 km² of existing farmland and 45 km² of newly cultivated land. Fourteen separate tanks — traditional Sri Lankan irrigation reservoirs — are fed by the scheme, reviving an ancient system of water management that dates back millennia.

This irrigation component is significant for smallholder farming communities in the east, who depend on monsoon rains for paddy cultivation. By providing a more reliable year-round water supply, the project aims to reduce dependence on rainfall variability and expand the agricultural frontier in the region.

What is the history and funding of the UOMDP?

Planning for a hydropower scheme on the Uma Oya dates to 1989, when Sri Lanka's Central Engineering Consultancy Bureau completed initial feasibility studies. Construction did not begin until April 2008, when former President Mahinda Rajapaksa and Iranian President Mahmoud Ahmadinejad jointly inaugurated the project. Notably, the foundation stone was laid before an Environmental Impact Assessment (EIA) had been obtained — a fact that attracted sustained criticism from civil society and environmental organisations.

The EIA, prepared by the University of Sri Jayewardenepura, was submitted in November 2010. During the mandatory 30-working-day public review period, the Central Environmental Authority received numerous objections from environmental groups who argued the assessment was inadequate. Despite those objections, the CEA granted environmental clearance and construction continued.

Financing for the project was provided primarily by Iran: approximately 85% of the estimated total cost of USD 529 million (roughly Rs. 80 billion at the time) came from Iranian government funds, with Sri Lanka covering the remainder. The involvement of Iranian contractors and funding made the project geopolitically notable, and it proceeded across multiple Sri Lankan administrations and significant changes in the bilateral relationship.

After years of construction delays, the completed complex was officially inaugurated on 24 April 2024 by Sri Lankan President Ranil Wickremasinghe and Iranian President Dr. Ebrahim Raisi in a ceremony that marked the project's transition from construction to operational status.

What environmental and social concerns surround the project?

The UOMDP has not been without controversy. The Uva Province contains sensitive highland ecosystems, and the Uma Oya river basin connects to the upper catchments of ranges that border protected areas such as Horton Plains National Park. Environmentalists raised concerns at the EIA stage about the potential impact of reduced river flows on downstream ecosystems, groundwater recharge, and biodiversity.

During construction, communities in the Uva highlands reported subsidence and cracking of houses in villages above the tunnelling routes — reportedly caused by groundwater disturbance from the boring operations. These incidents led to compensation claims and generated considerable local discontent. The project therefore stands as a case study in the tensions between large-scale infrastructure development and the rights and wellbeing of communities living along the project corridor.

How does the Uma Oya project fit into Sri Lanka's energy landscape?

Sri Lanka has a long tradition of hydropower development, drawing on its wet-zone highlands to generate clean electricity. Projects like the Randenigala Dam on the Mahaweli River established the template for large reservoir-based generation; the UOMDP extends this model into the Uma Oya basin. With 120 MW of installed capacity and an estimated annual output of 231 GWh, the complex is a mid-scale addition to the national generation mix — significant for the Badulla and Uva regions, which have historically relied on power imported from the Western and Central Provinces.

In the context of Sri Lanka's broader push toward renewable energy and reducing fossil-fuel dependence, the UOMDP's hydropower component aligns with national policy goals. However, analysts note that large-scale hydro projects carry their own ecological footprint, and the balance between renewable energy ambitions and environmental stewardship remains an ongoing policy debate.

Can visitors see the Uma Oya Hydropower Complex?

The Uma Oya complex is an active infrastructure facility and is not a conventional tourist destination. The power station is underground, and both the dam sites and tunnelling infrastructure are in restricted zones. However, the surrounding Uva Province landscape — rugged highland terrain, tea country, and the scenic rail corridor near Ella — is extremely rewarding for independent travellers.

The Badulla District, where the project sits, is within easy reach of Ella, one of Sri Lanka's most popular highland towns. Travellers who appreciate large-scale engineering and the intersection of infrastructure and nature may find the story of the UOMDP a fascinating context for exploring this part of the island, even if access to the facility itself is limited.