The Chicago River has proven itself fit for swimming. But what about raising a family? No one’s ever tallied the number of larval fish in the waterway, until now.

In a lot of ways, the history of the North American beaver is interwoven with the history of Chicago.

Freshwater mussels can be a river system’s best friend, but they’re missing from long stretches of the Chicago River. Here’s a look at one effort to reintroduce them.