Environmental conditions in Lake Aurevann, the Trehørning watercourse and Lake Søndre Heggelivann 2015 with focus on cyanobacteria and odor problems

Summary

In 2015, NIVA conducted a survey of the conditions in the Trehørning watercourse and Lake Søndre Heggelivann, in cooperation with Asker and Bærum waterworks and Bærum municipality, on assignment from the latter. 6 rounds of sampling were made from May till September, where relevant parameters for surveillance and environmental conditions and suitability for drinking water sources was measured. Focus was put on the algal composition in the lakes, and to cyanobacteria, to reveal potential causes of the odor problems that occur from time to time in Aurevann and in the drinking water. Data from 2015 is compared with previous surveys (1991, 2002-2003 and 2004) to reveal any changes.