The tank, 280-acres in extent and supplied by Rathambala Oya, is located within the Anavilundawa ramza wetland.
It also supplies water to seven other smaller tanks in the area, which altogether irrigate 1,027 acres of paddy land.
Katupatha Wewa, also supplied by Rathambala Oya, should release waters, as per an agreement, to Anavilundawa Wewa.
But, that has not been done for several years now, although Katupatha Wewa has enough water, according to farmers.
During the recent rains, Anavilundawa Wewa overflowed.
However, this and the other tanks cannot maintain their capacities due to being filled with silt.
The wildlife conservation department is not allowing a renovation of the tanks.
At present, farmers are pumping water from Rathambala Oya to Anavilundawa Wewa at a very high fuel cost.
When contacted, Puttalam district secretary N.H.M. Chitrananda said he was aware of the problem, adding that discussions would be held to obtain a solution.
He said that once the work on Sengal Oya movement is over, this problem will automatically be resolved.