Art which was a part of a satirical exhibition has been torn from its stand and thrown into the Medway.
The piece by Cold War Steve is currently on display at the Riverside Country Park in Rainham .
Medway Council hopes the artist, who has had worked displayed at Glastonbury , will help boost its UK City of Culture 2025 bid.
The work in question involves Tim Martin, the owner of the pub chain Wetherspoon.
Gillingham resident Peter Cook retrieved the piece after he spotted it floating in the river and has since handed it over to police.
He said: "I think it rather proves that art does cause reactions.
"It would have been very difficult for someone to pull down, there is a lot of strong adhesive on the stand.
"Someone would've set out to do this rather than an opportunist."
The vandalism comes after people raised concern over the messages behind some of the artworks and whether they were suitable for a location popular with families and young children.
Cold War Steve features political figures and topics such as Boris Johnson, Priti Patel and Brexit.
An incensed caller to the newsroom said his granddaughter had been left shaken by the image of "a near naked Boris Johnson next to a mass grave".
He said: "What the hell are they playing at having such 'art' on display?
"I go to the park to escape from things, not to have people's political opinions rammed down my throat. It's just disgusting."
Cold War Steve, aka Christopher Spencer, said: "The response we've had from the Medway exhibition has been amazing.
"People seem to really be enjoying the pieces but obviously there have been a few negative comments and some people don't think a nature reserve is an appropriate place for artwork of this nature.
"Whilst we agree that it could be seen provocative to some, it was intended to start a conversation, raise some eyebrows and the odd smile too.
"It inspired one person to rip the artwork down and throw it in the river, which is a shame, strong feelings of a different kind I suppose.
"The pieces come down this week anyway. Nothing lasts forever but I'm sure this won’t be the last art project of its kind to come by Medway. Fingers crossed for 2025."