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Faecal streptococci (enterococci) are valid indicators of faecal pollution of the environment. 
They were found in small amounts (not more than 1000 in 100 ml of water) in water samples 
obtained in the region and to the west of the Swina mouth. During the first cruise also the 
occurrence of the sulphite - reducing spore-forming anaerobes was noted, because 
Clostridium . species are the biological indicators of water quality, mainly Clostridium 
perfringens and Clostridium sporogenes. In the collected samples also saprogenic bacteria 
type were found of Pseudomonas aeruginosa, Pseudomonas maltophilia, Proteus vulgaris, 
Bacillus cereus and Bacillus subtilis. 
Also the Staphyloccocus aureus was determine. It occurred in the samples collected in the 
region of the Swina and Dziwna mouths within the range of 4 (min) do 415 (max) in 100 ml of 
water. Bacteriological examinations carried out between 23.08. and 28.08.97 during the 
second cruise proved the general decrease on the number of coliform, faecal coliform, 
enterococci and staphylococci bacteria. The sulphite - reducing spore-forming anaerobes 
bacteria were not found. 
The degradation of organic matter in the surface water was quick. High activity of Ciliata 
(protozoa) such as: Paramecium, Vorticlella, Campenella, Carchesium was observed. Apart 
from Ciliata (protozoa) also the fungi of were found which affect the water self-purification by 
natural degradation of organic substance. Collected results prove significant water 
contamination of the examined area by urban, faecal sewage. 
Conclusions 
The analysis of collected examination results proved significant water contamination in the 
examined region by faecal sewage, especially during the first cruise. 
Microscope analysis of the collected water samples showed high number and activity of 
protozoa which proves the increase on the water self - purification intensity. 
The highest values of total bacteria , total coliform bacteria , total faecal coliform were found 
in the region of the Swina and Dziwna mouths and spread also towards the Usedom and 
Ruegen coast.