Drowned Zombies Spawn Rate Too High!

Been playing for a few days and have a village located next to a river. Now, a few drowned zombies in the river is no big deal, but I’m talking about 500+ zombies completely filling the river. Just way too many zombies it’s ridiculous looking. 

 

I’ve included a screenshot below - there are this many zombies in every single part of the river around my village. Absolutely insane!