So your point is that since fines are not leveled at mother nature for allowing sediment into rivers it is legitimate for people and the companies they run to discharge sediment into our rivers. 
I see the comparison except that mother nature isn't making a profit at the expense of wildlife or the common ownership of our waters. But by your logic, since streams dry up, I could take all the water I want. Since volcanoes pollute, I can burn in my backyard even on days when people with breathing difficulties end up in emergency rooms. 
Now of course, mother nature also produces massive die-offs of species. By that logic, our actions which cause extinction are not to be criticized - its like mother nature. In fact, since animals kills each other, war is not to be critiqued. Even our own extinction is just part of the natural order.