Impact of Climate Forecasts on the Microbial Quality of a Drinking Water Source in Norway Using Hydrodynamic Modeling

This study applies hydrodynamic and water quality modeling to evaluate the potential effects of local climate projections on the mixing conditions in Lake Brusdalsvatnet in Norway and the implications on the occurrence of Escherichia coli (E. coli) at the raw water intake point of the angstrom lesund water treatment plant in the future. The study is mainly based on observed and projected temperature, the number of E. coli in the tributaries of the lake and projected flow. The results indicate a gradual rise in the temperature of water at the intake point from the base year 2017 to year 2075. In the future, vertical circulations in spring may occur earlier while autumn circulation may start later than currently observed in the lake. The number of E. coli at the intake point of the lake is expected to marginally increase in future. By the year 2075, the models predict an approximately three-fold increase in average E. coli numbers for the spring and autumn seasons compared to current levels. The results are expected to provide the water supply system managers of angstrom lesund with the information necessary for long-term planning and decisions in the protection of the drinking water source. The method used here can also be applied to similar drinking water sources in Norway for developing effective risk management strategies within their catchments.