MICROBIOLOGICAL STUDY OF BALTIC SEA AND GULF OF RIGA COAST BATHING WATERS

Abstract

This report focuses on the studies o f the bathing water microbiological quality in Latvian coastal zone of the Baltic sea and the Gulf of Riga in May-October, 1998-1999. The microbiological studies has been done in the different coastal zones of Kurzeme and Vidzeme, downstreams o f small rivers and biggest rivers Venta and Gauja, discharges o f wastewater treatment plants and the public bathing waters in Ventspils and Saulkrasti municipality area to assess their quality according to the EU Blue Flag and Latvian National Standard criteria. The microbiological examinations were carried out in accordance with the International Standard Methods. A complex of indicatororganisms - total and thermotholerant coliforms (E.coli), streptococci, and heterotrophicplate count (37°,21°C) has been tested. Water quality in the Kurzeme has been found much better on the beaches of the Baltic sea than the most urbanised beaches of Gulf o f Riga. The quality o f the Ventspils public bathing waters has been evaluated as very good (80-100% o f data). Whereas as a result of anthropogenic load only 61-82% o f data conforms the obligatory requirements of the bathing water quality in Saulkrasti coastal zone. In the study the microbiological pollution, sources and levels of their dynamics and hydrological factors are interpreted. The colour maps o f the bathing waters quality are presented.