Punjab Irrigation consultant M.H. Siddiqui told Business Recorder that in mid-1970s, the Tarbela Lake had the water storage capacity of 9 MAF which had been reduced to 6.581 MAF due to silting in the reservoir. Similarly the 5 MAF storage capacity of the Mangla Dam on river Jhelum had also come down to 4.5 MAF owing to sedimentation of the dam.
However, he said the water storage capacity of Mangla Dam after completion of the Raising Project increased from 4.5 MAF to 7.39 MAF and thus it will store 2.88 million acre feet of additional water during the current monsoon season. He said the filling of the Dam was recorded at 1,238 feet out of total 1,242 feet on Tuesday. The reservoir has stored 7.1 MAF of water till now and it is likely to fill up to its maximum level during next 10 days. The dam would add 644 million units of low cost electricity annually from the existing power house. Additional benefits of the project have been estimated at Rs 18 billion per annum.
WAPDA engineers said rising of Mangla lake by 40-ft has also been playing a pivotal role in mitigating floods in addition to 2.88 MAF additional water storage facility. Due to raised level, the Project has held back a large quantum of water of the river Jehlum and its tributaries to the tune of 2.5 Million Acre Feet of water, which saved the low lying areas of Jehlum River from averting additional flood hazard. The Mangla lake still has 0.29 MAF additional storage capacity for conservation though Tarbela Dam and Chashma reservoirs have filled up to their maximum capacity.