Analysis of water pollution of the Pur and Taz rivers, their ecological state and chemical runoff was carried out both on the basis of regime information and expeditionary observations. In this paper, we present the results of a hydrological and ecological assessment of the state of the Pur and Taz rivers on the basis of published data. It is noted that synchronous oscillations are not characteristic for the runoff of the rivers under study. This is due to the natural regulation of their basins. The degree of pollution of the Pur River is higher than for the Taz River. The waters of these rivers are defined as dirty. It is emphasized that the Pur River keeps in a transitional state from equilibrium to crisis, whereas the ecosystem of the Taz River is in a crisis. Changes in the biotic component of river ecosystems under anthropogenic impact cannot currently be reliably determined due to the lack of modern results of hydrobiological monitoring.