Why Are China's Lakes Turning Green?

In Dianchi Lake in the southwestern Chinese province of Yunnan, something strange is happening. Instead of a shimmering mirror of cobalt blue or even a murky opaque black, the lake’s surface is an unmistakable and unsettling shade of green. Like many Chinese bodies of water, the lake has been subject to eutrophication - a process during which the water turns green thanks to an influx of agricultural run-off and, above all, animal waste.

Though most notable in China, eutrophication is a phenomenon which has plagued lakes and reservoirs all over the world, including in the UK in the late 1900s. What makes it such a troublesome conundrum in China right now is the rapid urbanisation of the population, the popularity of porcine produce and improper methods of waste treatment, storage and destruction.

Slipping standards

China has, in some ways, become a victim of its own success. The massive population increase and attendant economic boom led to the government revamping its agricultural industry at the turn of the millennium. However, in transitioning from family-owned farms to consolidated collectives which are much bigger in size, many of the old environmentally-friendly practices have been left by the wayside.

For example, a 2016 study found that as much as 70% of the manure generated by larger farms was deposited directly into nearby rivers and streams. In the 1970s, when the vast majority of agricultural activity was undertaken by isolated families working alone on single farms, that percentage was just 5%.

Government intervention lacking

These newer, larger farms don’t often bother with the expensive and time-consuming process of converting manure into digestate, which can be used as organic fertiliser, even if they have the machinery onsite. That’s because it hasn’t been made compulsory by the government and can often entail higher costs than the fertiliser itself recoups at market.

It’s easy to understand why the government wants to encourage smaller farms to band together to create larger collectives, as this often alleviates poverty, pools resources and increases efficiency. It’s also evident that the government is unwilling to impose unachievable environmental targets on farms which can ill-afford to meet them. But when the technology to clean up animal waste already exists and is in place, all that’s needed is a subsidy or other government incentive to get the ball rolling.

Green lakes the real victim

This unwillingness to recycle animal waste or undertake sustainable sludge destruction practices is ultimately to the detriment of Chinese bodies of water. A visceral reminder of the problem surfaced in 2013, when around 16,000 dead pigs floated down the Huangpu River to Shanghai after being poisoned by water supplies. Despite the stark image, many Chinese do not connect their love of pork to the contamination of the water all around them.

In order to combat the eutrophication of Lake Dianchi and other bodies of Chinese water, a multifaceted approach must be adopted. Consumers must amend their eating habits by limiting their intake of pork, thus reducing demand and eventually decreasing supply, while farmers must also do their bit to ensure that the waste produced by their operations is dealt with appropriately. Only then will the lakes turn back to their shimmering best.