The new vented dam at Thumbe that is unable to occupy land to be submerged as it has not been acquired has another drawback with regard to storage of water.
Pointing this out in the Karnataka Development Programme Review Committee meeting here recently, J.R. Lobo, MLA, Mangaluru City South, said that engineers who built the dam fixed the weir level gates 1 m. above the dead storage level of the dam. It would only result in accumulation of silt up to 1 m. high in the dam resulting in intake wells, through which water would be drawn by pumps, covered under silt. In addition, the maximum storage level which is 7 m. would be actually reduced by 1 m. Once silt gets accumulated, the actual maximum storage level would be only 6 m.
Mr. Lobo said that presently, if water was stored only up to 5 m., the dam could hold water only up to 4 m. after accumulation of silt. Hence, it would not make any difference as the maximum holding capacity of the old vented dam was also up to 4 m. level.
Mr. Lobo, who was former Commissioner of Mangaluru City Corporation, said the weir gates have been fixed at the centre of the dam. If the same had been fixed in the dead storage level with additional gates on both ends of the dam, silt would have drained out in the rainy season. If intake wells come under silt, the pumps would get damaged.
An engineer of the Karnataka Urban Water Supply and Drainage Board (KUWSDB) said he would study the issue and address it.
B. Ramanath Rai, Minister in-charge of Dakshina Kannada, asked the Minor Irrigation Department officials to send a proposal to the government seeking funds for the maintenance of all 248 vented dams across the district. An official of the department told the meeting that 53 vented dams now faced shortage of planks to arrest water for summer. It required about Rs. 84 lakh.
Stressing upon the need to build more vented dams to recharge ground water, the Minister said drilling bore wells would only threaten the ground water source in the district in the near future.
