The impact of human activities and regional droughts on water resources in Mongolia over the past several decades has been profound. Water use for irrigation, mining etc., and human activities in watersheds such as deforestation, have resulted in substantial reductions in river flows and flow regimes, water level reductions or complete drying of many lakes, and lowering of ground water tables. For example, the annual average flow of the Tuul river has been reduced by 32% and roughly half of this reduction may be attributed to the cutting of 270 km2 of forest in the watershed of this river 40-50 years ago.

It was reported (Batjargal 1992) that several lakes in the southern part of Mongolia, for example Onggyn Ulaan, Orog, Dzagyn Shal, have been severely depleted or have dried out completely. But since 1993, the situation has changed due to less intensity of drought and most of those lakes have already been recovered. In addition to the obvious ecological disruption caused by lake drying or level reductions, human economic activities on lake-shores, such as the mowing of reed for fodder, have significantly impacted the ecology and wildlife of many lakes.