men discarding wanted in an conversion range protect to that tea & discarding is similar to throwing & garbage means waste ->  humans throwing garbage in an environment causes harm to that environment  a mind of land is a mean of percentages & a stream is a kind of moving body of water -> a stream is a kind of environment a stream is a kind of environment  men throwing artifact in an images form protect to that spectrum & a stream is a kind of environment -> humans throwing garbage into a stream causes harm to the stream