aOUR STAFF REPORTER LAHORE Water and Power Development Authority (WAPDA) generated 31.45 billion units of hydel electricity during the fiscal year 2010-11, registering an increase of 3.84 billion units as compared to 2009-10.This additional contribution of low-cost hydel electricity by WAPDA to the national grid saved about Rs. 41.64 billion to the national exchequer. This increased hydel generation was made possible owing to efficient operation and management of hydropower stations and availability of more water in the reservoirs. According to the data, more than 31.45 billion units of hydel electricity were contributed to the system during the fiscal year 2010-11, while about 27.61 billion units were supplied during the year 2009-10. Tarbela, the largest hydel power station in the country, generated 15.833 billion units during 2010-11 while 13.833 billion units in 2009-10. Similarly, Ghazi Barotha, the second in line, produced 7.356 billion units against 6.715 billion units, Mangla, the third in row, 5.953 billion units against 4.638 billion units, and Warsak and other small hydel power stations shared 2.308 billion units in 2010-11 against 2.425 billion units during 2009-10. It is pertinent to mention that the installed capacity of hydel power generation in the country stands at about 6,500 megawatt (MW)about one third of the total installed capacity.