Ancient Period	Colonial Period	(1948-1936)
(1963-1969)	(1969-1977)	(1977-1994)
(1994-1998)

Ancient Period

1 BC	First Dam across Mahaweli River by King Kootakannatissa at “Meenwila”. (Manampitiya)
67 AD	Construction of Elahera Canal by King Vasba
275-301 AD	Elahera Canal extended to Minneriya – Kaudulla by King Mahasena
368 AD	Angagamedilla diversion dam across Ambangaga at Abgamedilla by King Upatissa I
571-604 BC	First Diversion of Mahaweli water through “Manimekhala” now Minipe Left Bank Canal, the Trans-Basin Canal constructed by King Agbo I
853-857 AD	Minipe Ela extended by 47 miles by the King Sena II
1153 AD	Parakrama Samudrha augmented from the canal called “Akasha Ganga” which originated from Angamadilla by King Parakramabahu I

Colonial Period

1865-1872	Sorabora Wewa restored
1872-1877	Elhera Canal and Allai Tank restored
1877	Central Irrigation Board established
1900	Irrigation Department established
1902	Irrigation Department commenced investigations on feasibility of the diversion of Mahaweli waters to Malwathuoya Basin.
1928	The Allai Tank (Seruwewa) was augmented Mahaweli waters through the Kallar Ela via an anicut constructed across Werugallaru, a branch of Mahaweli River
1935	Rehabilitation work of Elahera and Minipe Canal commenced.

After Independence

(1948-1936)

1950	Irrigation Department commences Studies on Mahaweli diversion.
1954	Government of Sri Lanka seeks assistance from the Canadian Government under the Colombo Plan for a Water Resources Survey.
1957 Oct 7	The Walawe Scheme inaugurated.
1958-1962	Engineering studies for the diversion of Mahaweli River carried out by the United States Operation Mission (USOM. now known as USAID)
1962	A joint report titled “Feasibility of Development, Mahaweli Ganga Trans-Basin Diversion Scheme” issued by the Irrigation Department and USOM.

(1963-1969)

1963	The government decides to make a request to the United Nations to carry out an independent study.
1964-1968	A Survey of the land and water resources of the Mahaweli Ganga by the UNDP/FAO.
1968 Sep 30	Mahaweli Ganga Diversion at Polgolla commissioned.
1969	The UNDP/FAO final report of the Mahaweli Plan released.

(1969-1977)

1970 Feb 28	Mahaweli Diversion Project inaugurated at Polgolla.
1970 March 21	Mahaweli Development Board Act No 14 of 1970 passed.
1970 May 3	Mahaweli Authority area gazetted
1970 May 10	Construction work of the Polgolla complex started
1972 Jan	Polgolla complex commenced
1973 March 30	Bowatenna Complex inaugurated
1973 May	Kotmale feasibility study commenced
1974 Feb 15	Construction work of Huruluwewa feeder canal commenced
1976	Construction work of Polgolla – Ukuwela Tunnel completed
1976 Jan 08	The Polgolla complex commissioned
1976 March 18	Bowatenna Tunnel opened
1976 April 3	Kalawewa – Balaluwewa sluice opened
1976 May 23	First release of Mahaweli water from the Kandalama Tank
1976 Oct	First release of diverted Mahaweli water to the Huruluwewa reservoir
1976 Nov 7	Mahaweli water released from the Minneriya Tank to Kantalai
1977 Sep 9	Agreement signed with USAID for funding System H.

(1977-1994)

1977 Oct 12	The government decision to accelerate the Mahaweli Programme.
1978 Jan 30	Construction work of the Ulhitiya Project commenced
1978 Aug 14	The Maduru Oya Project commissioned
1978 Sep 7	Ministry of Mahaweli Development was established
1978 Oct 15	Galnewa New Town declared opened
1978 Dec 21	EEC Agreement to finance the System G Development signed.
1979 Feb 4	Construction work of Kotmale Project commenced
1979 March	Construction work of Ulhitiya commenced
1979 April	Mahaweli Authority of Sri Lanka established.
1979 Aug 30	The agreement with the USAID for re-forestation signed
1979 Oct 20	Jaya ganga sluice of Kalawewa opened
1980 March 23	Construction work of the Victoria Project commenced
1980 April 10	Work on the Victoria Dam & the Tunnel commenced
1980 April 16	World Bank – IDA Loan signed
1980 June 04	Mahaweli Settlement Division established
1980 June	690 settled in System C
1980 June 14	Maduru Oya Project commenced
1980 Oct 31	ADB Loan for Mahaweli Area Road Development signed
1980 Nov 10	TAMS Report (Mahaweli Environmental Study) completed
1980 Jan 23	EEC Agreement for Development of Zone 2 signed
1981 Apr 16	Uda Walawe Project handed over to MASL
1981 July 31	Galnewa Central College started
1981 Nov 11	Agreement for Randenigala Construction signed
1981 Dec	Mahaweli Economic Agency established
1982 Nov 21	Work on the Randenigala Project inaugurated
1983 Apr 9	The Ulhitiya Reservoir commissioned
1983 Jul 2	The sluice gate of the Maduruoya Reservoir opened
1984 Apr 4	Waters of the Mahaweli in the Victoria Reservoir impounded
1984 Apr 21	The Minipe Right Bank Canal commissioned
1984 Aug 27	The first charge of hydrel power from the Victoria reached the National Grid
1984 Nov 17	The Kotmale Reservoir impounded
1985 Apr 12	Victoria Project commissioned
1985 Aug 23	The Kotmale Project commissioned
1986 Mar 23	The Randenigala Reservoir impounded
1986 Mar 23	Work on the Rantambe Project commenced
1986 Apr 11	Giradurdkotte New Town opened
1988 Mar 28	System “L” gazetted as a special Area under Mahaweli Authority
1988 Nov 11	Welikanda New Town opened
1990 Mar 10	Kotmale New Town opened
1990 May 28	The Rantambe power complex commissioned

(1994-1998)

1994 Jan	Padalangala – Suriyawea – Mirijjawila New Road in Walawe commenced
1994 July 4	Engineering studies for Walawe Left Bank commenced
1995 Aug 31	OECF loan agreement for rehabilitation and provision irrigation facilities in Walawe Left Bank signed
1996	Negotiations with Kuwait Fund assistance for Moragahakanda Project commenced
1996 Feb 11	Padalangala – Suriyawewa – Mirijjawila new road network in Walawe opened
1996 May 17	EEC Grant for rehabilitation of Systems C & G signed
1996 July 7	Netherlands Grant for Mahaweli System “C” multifunctional Households environmental Project signed.
1996 July 31	OECF Loan Agreement for provision of irrigation facilities to Walawe Left Bank extension area and rehabilitation work of the Walawe reservoir signed
1997 Feb	Initial work on rehabilitation work in System H commenced
1997 Aug 6	Huruluwewa Feeder Canal gazetted as Special Area under the Mahaweli Authority.
1997 Aug 18	OECF Loan Agreement for Mahaweli System C Upgrading Project was signed.
1997 June	A separate Ministry of Mahaweli was once again established.
1997 Dec	Implementation of World Bank and Government of Sri Lanka Project on restructing of the Mahaweli Authority commenced
1997 Dec 6	Walawe Left Bank Development work inaugurated
1998 Jan 2	System B Model Zone Development inaugurated