"A fast-spreading, foul-smelling, blue-green algae smothered a lake in eastern China, contaminating the drinking water for millions of people and sparking panic-buying of bottled water, state media said Thursday...The algae bloom in Lake Tai, a famous but long-polluted tourist attraction in Jiangsu province, formed because water levels are at their lowest in 50 years, leading to excess nutrients in the water, Xinhua said." The result is reported as foul odored, yellow water emanating from the water taps, and showers that make you smell like dead algae. For a public water system with adequate surface water treatment technology, including secondary polishing using activated carbon beds for color, odor, and taste removal, this would be a fairly easy problem to cope with. It's done all time in North America by cities that rely on hyper-eutrophic lakes for their water - just takes advance planning to get the sand filters big enough and carbon in place in time for the peak algal blooms. Apparently the Chinese city did not have that option. At any rate, according the the Dow Jones Newswire report (by subscription): - "The city has placed a ban on price hikes and threatened hefty fines to violators, the report said. A Wal-Mart store imposed rations of 24 bottles per person,..." The larger point is that wherever drought and increased withdrawals for consumptive uses or watershed diversions are reducing surface water volumes at the same time that inadequately treated human sewerage and animal waste are being discharged to the same system, this is increasingly prone to happen. Climate change may contribute, but blaming climate change won't help. What could help would be a Chinese version of the US Clean Water Act, leading to a quantitative look at where the excess nutrients are coming from, and the development of a phosphorus control plan with firm deadlines (based on the nutrient loading estimates). Image credit::Lake Tai shown in satellite imagery, false color infrared most likely, from University of Washington
Footnote: we're unsure about the color signatures of this particular satellite photo but typically the dark blue to blue-grays denote wet soils or water and vegetation (think green and cool and pleasant) while the red denotes bare rock or soil or hot rooftops and roads or streets (hot and dry or barren and eroded). Such color signatures change with seasons and weather.