Lake Opuha was busy with campers and boats over Waitangi weekend 2021. A potentially toxic algae has been found in South Canterbury's popular Lake Opuha and drinking water or eating fish from the area should be avoided. South Canterbury Medical Officer of Health Dr Ramon Pink says monitoring has identified a bloom of potentially toxic planktonic cyanobacteria algae in the lake prompting the health warning and supporting signage. The lake area, which has several boat ramps, campgrounds and picnic areas, is also known for offering good trout fishing, but the warning from Community and Public Health says fish and shellfish can concentrate toxins and their consumption should be avoided.