That's water gushing out of a broken water main at the side of the street. Chicago has been plagued with water main breaks this winter, including another one just north of my workplace at Addison and California and one on Lake Shore Drive and Belmont near where I live that forced a residential skyscraper to be evacuated for several days; the extraordinarily cold weather can be blamed, but it's just as easy to conclude that the water infrastructure is perhaps not as robust as it could be. Chicago is like most American cities in that the water system is about a hundred years old, and upgrading it with a hundred years of valuable real estate dropped on top of it is as difficult and unsexy as it is necessary. I did my part by calling 311 and notifying the water department about the leak, for whatever that's worth, so perhaps it's thanks to me that traffic will be snarled up on California for the next few weeks while they fix it.
(The famous flood of 1992 wasn't related to the water system, incidentally. It more sort of involved water.)
Since I was looking up that photo anyway, I also went ahead and threw some photos I took when I visited my sister in Minneapolis last Thanksgiving into an album. They're mostly of the Minneapolis Sculpture Garden, though there is one of a giant LEGO dinosaur at the Mall of America and one of the fabled albino squirrel that lives in Loring Park.
Hey, Jon: This is that cool footbridge I was telling you about that one time.