Average total river discharges are estimated at between 39 billion m3/y and 42 billion m3/y, with 95 per cent being discharged into the Adriatic Sea and 5 per cent into the Ionian Sea. Groundwater resources are estimated at between 9 billion m3/y and 13 billion m3/y. Around 626 reservoirs provide a designed capacity of 560 million m3.