Is it safe to swim in Chicago River? Hundreds just did for this cause

Hundreds of people went against a nearly century-long tide to swim in the Chicago River on Sept. 22.

The event, which was put on for ALS research, marked the first open water swim in the river in 98 years, according to A Long Swim , a nonprofit that organized the event.

The Chicago River, which famously runs through the city's downtown and is annually dyed green for St. Patrick's Day , has had a long history of pollution . After decades of cleaning efforts, the river is now considered safe for swimming, according to event organizers.

"The river has been restored as one of our city's greatest assets. Today shows how far we've come in reclaiming our environment for future generations," Johnson said in opening remarks at the event.

Chicago River Swim raises money for ALS research