Uspen DistrictUspen is a district of Pavlodar Region in northern Kazakhstan. The administrative center of the district is Uspenka. Many Kazakhstan Germans live in this area. Population:GeographyLake Ulken Azhbolat, a briny endorheic lake, is located in the district. The Burla river flows into the eastern lakeshore. Lake Chagan straddles the Kazakhstan–Russia border, and Ulken Tobylzhan lies further south.