Tunisia's "White Gold"

It is a truth universally acknowledged that Tunisia has scarce or no natural resources at all but it appears that Tunisia has a precious product, the White Gold!, well do not be so enthusiastic since the White Gold I am talking about now is but mere MILK!. It's been more than two weeks I guess that this product disappeared from supermarkets and what are the real reasons? No body knows...

Photo Quiz

This photo is taken somewhere in Tunisia. For those who will find the answer, could you please explain the reason behind this reddish brown color of the water?