08/08/2014 09:23 BST | Updated 07/10/2014 06:59 BST

Eerie Lake Erie: Factory Farming Is Causing Big Problems Far Beyond the Farm

You may well have picked up the latest news from Toledo in Ohio, USA, where a severe toxic algal bloom - said to be at least in part due to industrial farm pollution - is causing havoc with local water supplies, leaving half a million people without safe drinking water.

Drinking the water from Lake Erie, in Toledo, could result in vomiting, diarrhoea and other health problems. Boiling the water won't remove the toxins, and not only have residents been told not to drink the water, but they have also been advised to not brush their teeth with it!

America's intensive agriculture practices take part of the blame for this disaster and it has been reported that factory farm runoff fed by fertilisers is the number one contributor. With a combination of factory farming, sewage, storm water runoff and industrial pollution, large heat zones have been created. The pollution where water temperatures are much warmer causes algae bloom.

It's a phenomenon seen around the world and a sign of serious pollution; tiny organisms multiply rapidly, thanks to polluting nutrients getting into the water, before dying and giving way to more of the same. The decaying mass of dead algae strips the water of its oxygen affecting aquatic life in its wake.

When I was researching my book Farmageddon, I visited a similar algal bloom disaster, in China. The third largest freshwater lake in China and a popular tourist destination, Lake Taihu was so polluted that the fish and surrounding wildlife were being killed by the toxic algal bloom. The cause? Pig farming effluent.

Pollution from factory farms was flowing straight into the lake and employees were desperately attempting to keep the algae at bay. It was reported that 2,000 intensive livestock farms were contaminating the Lake's water basin. When I stood on the lakeside, my boots were covered in thick oily-green slime and the water was lined with what looked like green paint. The lake had been hit by an algal bloom. It wasn't the first time algal blooms had hit this beautiful lake. In 2007, it was hit so badly that over two million people had their drinking water cut off. The lake has since become a symbol of China's deteriorating water quality. Despite this, China is investing heavily in industrialised agriculture, at the same time as it is undergoing a food confidence crisis.

Factory farming means large scale grain production, which equals fertiliser use on a huge scale - not only on the livestock farms. America's Great Lakes, China's third largest lake - the problem is universal. We have to stop this. Stop the misuse and overuse of fertilisers. End the cruelty and stupidity that is factory farming. It will not only help the animals, but clearly, human health as well. What is more precious to us than drinkable water?