Kuwait oil lakes

In January and February 1991, at the end of the Gulf War, retreating Iraqi forces set fire to between 605 and 732 Kuwaiti oil wells. The fires burned for months: the first were put out in early April, and the last well was capped on 6 November 1991. At the peak, 4–6 million barrels of crude were burning each day.

The oil that did not burn, estimated at 25–50 million barrels, collected in desert depressions and formed about 300 lakes. Soot and oil droplets fell on the sand and hardened into a crust ("tarcrete") covering nearly 5% of the country's land. The Wikipedia entry puts the contaminated sand and earth at about 40 million tons.

Clean-up began much later, under the Kuwait Environmental Remediation Program run by the Kuwait Oil Company and funded with about 3 billion dollars of UN compensation money. Bidding opened in 2017 and the contracts for the southern zones date from 2021. Less contaminated soils are treated by bioremediation, more heavily contaminated ones by soil washing. The programme also covers mine clearance and revegetation: the target stated in September 2024 is to plant 8 million shrubs, grasses and trees.