I actually absolutely adore this idea. I feel like this game has so much potential and can go so far. And it's such a brilliant visual description of wastage. The music choice is all but perfect. Love the art-style chosen: reminds me of the old-school stick-man flash games that were amazing.
But I do have a few critique where I think there can be improvements:
1. I loved the music played during the level selector scene and I feel like it might sound really good if that continued into the game itself. But that's just a personal opinion xD
2. The gameplay needs a bit of work because there's a lot of idle-time/waiting. I saw a suggestion by Mikatte to take inspiration from pinball-type games and I'm in complete agreement. It'll just mean that there's continuous player involvement instead of having to just sit on our hands and wait for it to get over. Makes it more playable.
3. A speed up button would be really really well or maybe increase the amount of points one gets for catching poop. That'll also help improve the flow of the game.
4. The game is already really impactful, but to make it more, you could also have the river get filled with poop/trash when there's more wastage. It'll add to the already good visuals.
Overall, brilliant game and I loved playing it!