Canal shipping suffers from drought induced by El Niño. The Panama Canal uses 52 million gallons of freshwater per ship, with about 40 ships a day going through the canal. In Panama, authorities say reduced rainfall has damaged an economic asset that requires an abundant water supply. The lake at the top of the series of locks is dangerously low and authorities may have to impose restrictions on ship draft (depth of keel—a measure of load), requiring ships to off-load cargo before going through the canal. This would add cost to goods.