This paper comprises the results of examinations of the number of indicatory bacteria of pollution degree (TVC 20 degrees C, TVC 37 degrees C) and sanitary state (TC, FC, FS) in the water of the Kamionka, Maniowka, Wiatroluza and Piertanka Rivers in the north area of Wigry National Park in 1996 and the number of these microorganisms taken to Wigry Lake. The investigations were carried out at 3 sites situated on the Kamionka River (in Okuniowiec, below a group of "hucianskie" lakes, before the tributary to Pierty Lake), at 2 sites situated on the Maniowka River (in Lipniak and before the mouth to the Wiatroluza River), at 5 sites on the Wiatroluza River (in Wiatroluza, above and below the estuary of the Maniowka River, at the mouth to Krolowek Lake, between Krolowek Lake and Pierty Lake) and at 1 site situated on the Piertanka River (between Omulowek Lake and Wigry Lake). The obtained values of bacteriological indices of pollution degree and sanitary state were compared with the criteria of surface water purity estimation suggested in literature and their usefulness for recreation. The number of the examined indicator bacteria found in the present research shows significant water pollution (II and III class of purity) of the examined rivers in the region of rural areas and the improvement of purity degree along the river course. There were found leakages of pollution from cesspools in the rural areas (demonstrated by a significant number of FC in water of given sites) and flows from other arable-forestry-pasture-meadow catchment (which is expressed by a larger number of Streptococci than Escherichia coli) as a main source of water pollution of the examined rivers.
