For more than 50 years, Shell and associated companies have used the Niger Delta as a dumping ground for toxic oil and drilling byproducts, producing an environmental catastrophe so severe it will take up to 30 years and $1 billion to mitigate, according to a leaked United Nations report published Thursday.

Researchers with the U.N. Environment Programme spent three years pouring through records and sampling soil, fish, air and water in and around a 1,000 square kilometer area of the Niger Delta to determine how systemic the pollution had become.

They found that bodies of water, including drinking supplies, were over 1,000 times more contaminated than is allowed by law, and that most of the spill sites oil companies claimed to have cleaned up, weren't. They also found that much of the soil is contaminated down as far as five meters.

Drilling in Ogoniland has been shut down since 1994, when Shell and its affiliates were kicked out of the country over their history of pollution.

The report, which was commissioned by the Nigerian government and partially paid for by Shell, does not put blame on any particular company.

Read the full report, courtesy of The Guardian, below.

UN Environmental Assessment of Ogoniland

Image credit: Flickr commons.