The Mahaweli Development programme (Sinhala:මහවැලි සංවර්ධන වැඩසටහන) is known as the largest multipurpose national development programme in the history of Sri Lanka and is also considered as the keystone of the government's development programme since 1977.
The main purposes of carrying out the programme were generation of hydroelectric power, controlling flood, making irrigation facilities for dry zone cultivation, settlement of landless and unemployed families by constructing and developing physical and social infrastructure required for human habitation by using the waters of the Mahaweli River. Increase local agricultural production and create employment opportunities for the people were among the other expected purposes.
The Master Plan of Mahaweli Development Programme was prepared with the assistance of UNDP and FAO and recommended for step wise implementation over a period of 30 years. The programme, included irrigation development of about 365,000 ha and hydro power development of 470 MW in capacity. For the purpose of identification, the whole development area was divided into projects, referred to Systems A to M.
The first phase of the programme consisted of diversion headworks at Polgolla and Bowatenna, 40 MW hydro power plant at Ukuwela and an improved water supply to about 52,700 ha of existing irrigated land. The phase I was completed in 1978.
The step wise implemented Mahaweli Development Programme was would have lasted about 30 years from 1975. The newly appointed J. R. Jayewardene government in 1977 decided to speed up the programme and complete it within its term of office of 6 years. According to that the Accelerated Mahaweli Programme (AMP) was implemented with a revision of the Master Plan in 1977. Which was consist of 12 projects and mainly confined to four head works in initial works of the programme, including the construction of Kotmale, Victoria, Maduru Oya, Randenigala dams and the downstream development of about 60,000 ha in Systems B and C and the Minipe anicut, the Right Bank Trans basin Canal and the Ulhitiya and Ratkinda reservoirs. To implement the project plan in the balance areas proposed by the Master plan and also Gazetted areas, Mahaweli Authority of Sri Lanka was established in 1979 by an Act of Parliament with a mandate.
As the end of 1995, all the head works of the AMP had been completed and were functioning. Feasibility studies were scheduled to be completed in respect of the proposed Moragahakanda Project.