hilly said..You realise Bali is not in the Philippines

Bali rubbish on the beach comes from Java in our summer. I went in January it was feral, but in July not too bad in Kuta. Offshore winds made a difference. There are too many people in the world.
There has been raw sewerage going straight in the sea from cliff locations near Uluwatu for decades. Depends on sea conditions and time of year as to whether you'll notice it.
the rubbish on the beaches come from their own rivers flushed out on the monsoonal rains (our summer) as you said. It just piles up in the canals where they throw it (when not burning it) in the dry season, hence why it's less dirty looking in the water April-sept.
The problem is huge and super sad.
and I've only looked at travelling to Boracay (no waves, opted out), but looking just on scale, the financial cost of pulling that Duterte move to sort Bali out would surely be orders of magnitude greater.