The weeds provide the necessary habitat for black-fly, mosquitoes and snails, which are the vectors of water-borne illnesses such as bilharzia, river blindness and malaria.
en.wikipedia.org Though not as common, other regularly treated diseases include dracunculiasis, dysentery, river blindness or onchocerciasis, several kinds of pneumonia, dehydration, venereal diseases, and poliomyelitis.
en.wikipedia.org Other uses include retaining walls, temporary floodwalls, silt filtration from runoff, for small or temporary/permanent dams, river training, or channel lining.
en.wikipedia.org River turbulence has created deep pools beneath steep sandstone cliffs on the northeasterly bank.
en.wikipedia.org The river changed course quickly, so the state boundary did not change.
en.wikipedia.org