The evaluation of the degree of pollution and sanitary-bacteriological state of surface water in Wigry Lake, North-East Poland. Part III. Waters of Hanczanska Bay and the areas adjoing Wigry Lake

This work comprises the results of examinations of a number of indicator bacteria on the degree of pollution (TVC 20°C, TVC 37°C), sanitary state (TC, FC, FS), and usefulness for recreation of Hanczanska Bay and areas adjoining Wigry Lake. Adequate studies were made in 1997, a year after the start of 3rd degree sewage treatment in the Wastewater Treatment Plant in Suwalki. All of these bacteria in general were more numerous in the water of Hanczanska Bay, especially in spring-summer. In the waters of northern Ploso of Wigry Lake numbers of bacteria were only periodically numerous at some water samples. The highest percentage of pure water samples fulfilling the requirement for bathing waters was found at sites on the border between Hanczanska Bay and the waters of Northern Ploso of Wigry Lake; the lowest percentage was found at sites in Hanczanska Bay. Gradual decrease of TVC 20°C ( sometimes 37°C) with the distance from the mouth of the Czarna Hancza River towards south-east sites shows this direction of the movement of main water masses of the Czarna Hancza River. No significant differences in percentage of unpolluted water samples stated in Hanczanska Bay and areas adjoing Wigry Lake with a comparison of data from 1994-1996 years of investigation.