Syr Darya one of the most important rivers in Central Asia, Central Asia’s longest river, and second-largest by volume. By the time it nears the end of a twisting course that takes it through four Central Asian states, the Syr Darya has accumulated such high levels of agricultural runoff such as pesticides and fertilizers, industrial waste, and any number of other contaminants that some are warning that crops irrigated by the river in southern Kyzyl-Orda province should be burned.