There is a case in Slovenia currently unfolding regarding dumpings of poo poo.

2 weeks ago someone unloaded 200m³ of sewage treatment plant sediment in a forest. It was noticed because nearby downstream is a botanical garden, and there was a well for 5 farms that also got polluted.
It turned out that the sediment came from Ptuj sewage system, but it's not clear who is responsible for the operation. Normally most of Slovenia exported sewage to Hungary but they stopped accepting it last year, and there's no processing facility in Slovenia, so some resorted to illegal (and potentially dangerous) methods of disposing it somewhere people won't notice it.
But they noticed this time.

Since then, several other dumpings have been discovered – it is weird how nobody ever reported anything before that.