By Jackie Sheehan.

Over a two-week period in March, more than 16,000 pig carcasses were dumped in the Huangpu River by pig farmers in Jiaxing, alarming Shanghai residents downstream who rely on the river for much of their drinking water. City officials have insisted throughout that the water quality in Shanghai is normal – hardly a proud boast in much of urban China – and I must admit that no pigs were visible in the final week of march in the last section of the river which winds through the centre of Shanghai and on to the mouth of the Yangtze. The water was its usual shade of murky brown, but that’s mostly sediment, not filth. You can see the genuinely improved health of the rivers in Shanghai’s centre from any of Pudong’s glass and steel towers, looking down at the place where Suzhou creek (the Wusong river) meets the Huangpu, flowing under the famous Garden Bridge; today, the two rivers’ waters are indistinguishable in colour, while fewer than 20 years ago, Suzhou Creek ran black to the point where it met the larger waterway and its heavy pollution was diluted.

But official statements provided little reassurance to locals wondering how that sheer volume of diseased and decomposing livestock drifting from only 100 km away can have had no effect. Perhaps anticipating a challenge to swim in the Huangpu to prove its safety, Shanghai water authority head Shen Yiyun went one better by offering to drink water straight from the river, which might bring a flicker of admiration even from hard-to-impress Shanghainese; porcine circovirus may not be flourishing in the water, but many things still are that make it prudent to avoid getting any closer to it than the deck of the Dongchang Road ferry before it has undergone treatment.

16,000 is a lot of dead pigs, even if we accept the claim that nearly 6,000 were subsequently fished back out of the water in Jiaxing. But even in a normal year, as many as 4,000 might be dumped in the river with hardly any comment or complaint. Jiaxing’s pig farmers were supposed to deposit their dead animals to decompose safely in “non-hazardous treatment pools” – I’m sorry, were you enjoying that bacon sandwich? – until all 600 of these pits filled up from the natural wastage of the area’s intensive hog-raising. There’s now an organized collection of dead animals, but even so, some casualties have been going into the river – with the tacit knowledge of local officials, some say, who view it as a way to lift a quiet two fingers in the direction of Shanghai, the exporter of much air pollution to the Yangtze delta hinterland where Jiaxing lies. If we have to have your stinky air, you get to have our rotting pigs; it didn’t seem such an unfair deal from Jiaxing’s side of things.

The huge jump in numbers being dumped since early March was mainly due to an outbreak of porcine circovirus on Jiaxing’s farms, probably fanned by unusually cold weather, which sharply increased the normal death rate. However, it is also a sign that one other method of getting rid of diseased animals has now largely been shut off. Many of those pigs going into the river would, before a recent crackdown on the practice, have been sold off on the black market and passed into the food chain illicitly labelled as fit for human consumption. So for Shanghai’s anxious residents, it’s a case of diseased meat jumping out of the xiaolongbao and into the drinking water.

Preventing this recycling of unfit meat, as a victory for food safety in China after the gutter cooking oil, melamine in milk, excess antibiotics in chicken and other scandals, is to be cheered. But this is a rather thin silver lining in a more familiar tale of the difficulty in getting environmental standards enforced across borders and in the teeth of local-government’s preference for letting local businesses prosper and hoping to make enough money somehow to clean up the mess later on.

And providing services for getting rid of solid waste of all kinds in rural areas is still a relatively new task for local government. It is not in the very distant past that nearly all rural waste was biodegradable and could be thrown anywhere. The bumper crop of shredded plastic bags that now festoons every tree, shrub, and scrap of open ground across much of China’s countryside is a measure of development and of improving living standards for village residents, but also demonstrates how difficult it has been for local authorities to keep up with its consequences, especially when feeble central enforcement of environmental regulations clashes with economic imperatives closer to home.

Jackie Sheehan is Associate Professor in the School of Contemporary Chinese Studies, University of Nottingham.