Basnagoda

The Irrigation Department has been entrusted with the construction of a reservoir for storing water to be used in Gampaha, Attanagalla, Minuwangoda Integrated Water Supply Scheme which is implemented by NWSDB. The project proponent is NWSDB and the target population of 250,000 in Gampaha District will be served by the project with treated pipe borne water.

The project area falls in two administrative districts; Gampaha and Kegalle and spans over 6 Grama Niladari Divisions, which are located in Attanagalla Divisional Secretary Division of Gampaha District and in Ruwanwella Divisional Secretary Division of the Kegalle District. The dam is proposed to build at village called “Karasnagala” across Basnagoda Oya which is a tributary of Attanagalu Oya.

The contract value of the project is 2.347 billion Sri Lankan Rupees and the contract period is 18 months. The parties involving in the project is as follows;

Employer	Ministry of Irrigation
Implementing Agency	Irrigation Department
Funding Agency	Ministry of Water Supply / National Water Supply & Drainage Board
Contractor	Sinohydro Corporation Limited

Technical Details of the Project

Dam
GPS coordinates	LB 134153 E 212274 N
Maximum Height	20.3 m
Crest Length	136.5 m
Bund width	5 m
Type	C20 Fine Aggregate Concrete Masonry Gravity Dam
Reservoir
Capacity	5.51 MCM
Catchment area	37.6 km2
Area inundated at FSL	65 Ha
Area inundated at HSL	76 Ha
Full Supply Level	45.73 MSL
Dam Top Level	48.74 MSL
High Flood Level	46.90 MSL
Minimum operating Level	34.00 MSL
Reservoir bed level	28.18 MSL
Spillway
Radial Gates	3.29 m x 6.0 m
No. of gates	3
Weir Type	WES Weir