It is illegal to throw snowballs within the city limits.

The Law Explained

Wausau famously bundled snowballs into an ordinance banning the throwing of any projectiles, arrows, or stones on public property. The law was originally intended to stop hooligans from causing property damage or injuring pedestrians. After a viral media uproar, the city police actually released a video of themselves having a snowball fight to prove they don't strictly enforce it against children.