 Finally, the discharges radically reduce salinity levels, making the river temporarily uninhabitable by fauna and flora that are intolerant to fresh water.In 2013, heavy rains in southern Florida resulted in high runoff into the lake; rising lake levels forced the U.S. Army Corps of Engineers to release large volumes of polluted water from the lake through the St. Lucie River estuary to the east and the Caloosahatchee River estuary to the west.Thus the normal mix of fresh and salt water in those estuaries was replaced by a flood of polluted fresh water resulting in ecological damage.