Uma Oya Hydropower Complex

The Uma Oya Hydropower Complex (also internally called Uma Oya Multipurpose Development Project or UOMDP) is an irrigation and hydroelectric complex in the Badulla District of Sri Lanka. Early assessments of the project date back to 1989, when the first studies was conducted by the country's Central Engineering and Consultancy Bureau. The complex involves building a dam across Dalgolla Oya, and channelling water over a 3,975 m (13,041 ft) tunnel to Mathatilla Oya, both of which are tributaries of the Uma Oya. At Mathatilla Oya, another dam is constructed to channel 145,000,000 m3 (5.1×109 cu ft) of water per annum, via a 15,290 m (50,160 ft) headrace tunnel to the Uma Oya Power Station, where water then discharged to the Alikota Aru via a 3,335 m (10,942 ft) tailrace tunnel.

The construction of the complex was inaugurated in April 2008 by former President Mahinda Rajapaksa and President Mahmoud Ahmadinejad. The total project cost is estimated to be approximately US$529 million (approximately Rs. 80 billion), 85% of which is provided by the Government of Iran.

The project was officially inaugurated by the President of Iran Dr. Ebrahim Raisi and President of Sri Lanka Ranil Wickremasinghe on the 24th of April 2024.

History

In 2008 Sri Lankan government began the project with Iranian funding and the foundation stone for the project without obtaining Environmental Clearance for the project. Environmental Impact Assessment (EIA) Report of the Uma Oya Project was prepared by the University of Sri Jayawardhanapura and was submitted in November 2010. During the 30 working days the EIA was open to the public for review and comments Central Environmental Authority received many letters from environmental organizations who called the EIA inadequate. However despite the objections CEA gave clearance for the project.

The two pelton turbine generators of 60 megawatt are fed via a 600 m (2,000 ft) vertical pressure shaft, after passing through the long tailrace tunnel. 68,000 m3 (2,400,000 cu ft) of earth was cleared to create the underground Uma Oya Power Station cavern. The 120 megawatt power station will generate up to 231 GWh per year.

The 5,000 m2 (54,000 sq ft) switchyard premises is built at 504 m (1,654 ft) above MSL. Power from the switchyard is delivered over 21.5 km (13.4 mi) of double-circuit 132KV transmission line, consisting of more than 70 transmission towers, to the Badulla Substation.

The annual discharge of approximately 145,000,000 m3 (5.1×109 cu ft) of water from the power station is distributed out via a 3,335 m (10,942 ft) cross-basin tailrace tunnel for agriculture use on 15 km2 (5.8 sq mi) or existing land and 45 km2 (17 sq mi) of new lands, including irrigation of 14 separate tanks.