Purpose: Generalization of characteristics of the Yana Rive hydrological regimen and assessment of unfavorable and dangerous hydrological phenomena in the area of Ust-Kuiga township. The township is an important transport transshipment base between the three Yakut districts: Ust-Yanskiy, Verkhoyanskiy and Eveno-Bytantaiskiy, and is promising in terms of the development of the Sakha Republic main economic sectors, including development of gold deposits. Methods: Collection, systematization, processing and statistical analysis of published materials of hydrological observations at the Ust-Kuiga stand and at the nearest stands, located on the Yana River and having a long series of observation data. Results: Characteristics of water extreme levels and expenditures during different phases of hydrological regimen, data on ice phenomena and knowledge on the largest spate causing township flooding were obtained. It has been established that the number of years with open riverbed short duration (from 93 to 98 days), which’s the least favorable for cargo delivery by river transport, constitutes 20% for the years of 1938-1989. The cases of the Yana River flow complete cessation during a day or more constitute 40% (21 years) for the observation period (52 years). The riverbed freezing in winter and absence of water flow during 30 days or more was marked in 28% of cases. The longest period (109 days) without water flow was recorded in 1975. The largest spate in Ust-Kuiga happened in June 1996 when the whole township was flooded. By flooding height. it exceeded huge spate of 1968 by 1.3-1.4 m. Practical significance: The work results can find a use in engineering-hydrological research implementation, planning, construction and exploitation of economic facilities in the area of Ust-Kuiga township. The obtained hydrological information is in demand by river and road transports which provide for enterprises activities in the township.