I live in the beautiful Takahue Valley, and have always had a clean and clear river in which to swim. Usually. Some mornings there has been a lot of some soapy substance on the water, which clears after a while.
Last summer one day the river was brown and thick, awful. It cleared after a while. On investigation I found that a commercial company was digging metal out of the river and stirring up the mud.
I talked to someone at the regional council who checked it out and got back to me to say that these people were helping the flow of the river, and yet again, the river will clear, after a while.
Now someone has cut some random new tracks up a steep hillside, and we have enormous amounts of silt/soil coming down the river.
One of the tracks runs close to the river. When this was cut it weakened the hill and slipped on to the track. This was then cleared by a tractor pushing it into the river.