A health warning about toxic blue-green algae in Canterbury's Lake Pegasus has now been lifted. Health New Zealand issued the warning in December after concerning levels of cyanobacteria were detected in the lake. Recent testing showed levels had reduced and concentrations were below that of concern to public health. Dr Cheryl Brunton of the National Public Health Service said monthly testing would continue over winter, with fortnightly sampling to begin again in September. "The public will be informed if assessments indicate there is a risk to public health," she said. Algal blooms occur naturally but could increase rapidly during warmer months. When a warning was in place, people and animals were advised to avoid affected waterways. Exposure to blooms could result in skin rashes, nausea, and stomach cramps.