Case study Fiskevollbukta
The bay Fiskevollbukta is a popular recreational area in the Inner Oslofjord. The river Ljanselva flow into the bay and the water quality may be affected by discharges of combined sewer overflows (CSOs). The purpose of the study was to investigate concentrations of indicators of faecal pollution (Escherichia coli, Faecal/thermotolerant coliforms (FC) and Intestinal Enterococci) in the river Ljanselva and at two bathing localities in the bay. The bathing water quality at the rocks near the river mouth was classified as poor according to the EU bathing water directive. At the little beach located in the south the bathing water quality was sufficient based on all samples and excellent when data from days with > 10 mm precipitation last 24 hours were disregarded.
Two general advices may therefore reduce the risk of gastroenteritis of people swimming in the area: 1) Swim out from the little beach in the southern direction, i.e. away from the river mouth and 2) Avoid swimming 24 h after heavy rainfalls. The work has been published in VANN no. 4, 2013.