Which of these most threatens the waters of the niger river? industrial pollution nuclear pollution overcrowding erosion

It's between Industrial Pollution and Overcrowding due to the amount of waste that is produced in foreign countries, with no proper way of disposing it. Considering that Niger is of relatively poor status, I'd say that the leading threat to the Niger river is simply Overcrowding. With the large amount of people, and disposal of waste wherever they please, I'd say this is what makes the river a hazardous source to obtain water.