The paper focuses on the consequences of uncontrolled gravel mining from the bed of mountain streams. As a result of that river channels are destroyed and lose their armoring layer. When this armoring layer is destroyed natural river bed is no longer protected against excessive degradation and many hydraulic structures and flood protection river engineering works are in danger. More than that, living organisms are eliminated through the removal of natural habitat and many invertebrate have no space to live. The same with fish, which with river bed gravel bed armoring removed, have no room to lay eggs.