10.4122/1.1000001458 Ruth, O. Bacterial loading in the water of urban streams in Helsinki, Southern Finland DTU Library, Technical University of Denmark (DTU) 2005 Bacteria Escherichia coli faecal coliforms urban hydrology urban streams water quality University of Helsinki, Department of Geography en Conference full text 10.4122/1.1000001457 application/pdf 1 Little research has been done into the hygienic quality of urban waters in Finland, and virtually none during the winter, when smaller streams are covered by ice. This paper presents data on three urban streams in Helsinki compiled at weekly intervals throughout the year in the periods 1995-96 and 1998-99. The results suggest that water quality varies greatly between winters according to weather conditions, with fairly large quantities of bacteria passing into the streams with the melt water in mild winters, while water quality remains good in frosty winters. Bacterial loading was highest in summer in all cases, however, and counts of hygienic indicator bacteria in these streams in Helsinki were on average 10-20-fold and momentarily several hundred-fold relative to those in areas in a natural state, although concentrations were low relative to those in actual storm water. The majority of the bacterial loading was found to originate from the excrement of warm-blooded animals, particularly dogs and birds. The easiest way of improving water quality in the streams of Helsinki would be to draw the attention of dog owners to the problem and ensure more efficient removal of dog excrement from the streets.