A few years ago the city ran out of water.

Capetown.

As I remember they had no alternative sources.

If you google it there is a lot of detail about it and how it was resolved!

It's a shame, hopefully sorted soon. That's a lot of people impacted.

I remember reading in several places that during pre-invasion times, they had a large aqueduct which transported fresh water from the mountains to the heart of the city on the lake. Not ready, yet, to hear what has happened to the ancient marvel, the "Floating Gardens of Xochimilco" there.

Because the original lake system had brackish sections, the Mexica not only had to figure out a system (the aqueduct) to get adequate water to the city, they also developed an intricate dike system to prevent flooding of brackish water into the city during the rainy season.

Xochimilco is the only part of the lake that's left, but for how long indeed.