The other thread showing a truck crossing a stream has been getting a lot of comments.
It is pretty dramatic to see the vehicle actually in the stream stirring up the bottom and the stream banks but there are worse situation that often get ignored because they are slow steady silt sources.
This is not the work of "a few bad apples" doing something wrong.
It is a place where OHV users go up a steep pipeline right-of way that should not have an OHV trail on it. The vegetation get destroyed by traffic and then water runs down the "trail" and brings huge amounts of silt (over time) into a trout stream. This pic is at the bottom where the "trail" enters the stream at a crossing.
I believe the new public lands act and regulations may give authorities more power to address situations like this.