The world's largest earth-filled dam on one of the world's most important rivers - the Indus - is 103 km (64 miles) from Rawalpindi, Permits are required for visiting the Dam. Please contact Public Relations Officer. Water and Power Development Authority, Tarbela. It has the largest electricity generating power plant and has the two biggest spillways in the world Tarbela Dam is extremely impressive to visit particularly in July. August and September when the lake is full from the melting snows and monsoon rains and the main spillway is in use to carry the overflow.