At least 250 years ago, the lake was fresh water, and much of it would dry up during the period just before the Nile flooded again. A storm in 1770 breached the sea wall at Abu Qir, creating a seawater lake known as Lake Abu Qir. The salt waters were kept separate from Lake Mariout by the canal that allowed fresh water to travel from the Nile to Alexandria. As part of the Siege of Alexandria, on 13 March 1801, the British cut the canal, allowing a great rush of sea water from Lake Abu Qir into Lake Mariout. Lake Abu Qir ceased to exist, and Lake Mariout became brackish instead of fresh.