Lake Alexandrina and the Murray River at Goolwa have been the subject of a water quality alert for months because of a toxic blue-green algae that used to only occur in the tropics. Lake Alexandrina and the Murray River at Goolwa have been the subject of a water quality alert for months because of a toxic blue-green algae that used to only occur in the tropics. Environmental Health, Water Supply, Water, Rivers, Microbiology, Climate Change Latest business news