Industrial and residential waste and sewage from six cities has critically increased water pollution in the Anzali Lagoon in northern Iran.

The Ana website reports that in the past, fishing in the lagoon would yield up to 15,000 tons of fish annually. Now the number has dropped to 200 tons of fish that is often deemed unfit for human consumption due to high level of toxins and chemicals.

Large volumes of garbage are buried in Saravan Forest, leaking five to 17 litres of toxinsper second into the Zarjoob and Gohar Rood Rivers.

The two rivers then pass through the city of Rasht, where they are used for the disposal of large amounts of city waste before pouring into the Anzali Lagoon.

In addition, deforestation and erosion have helped wash large amounts of soil into the lagoon, so that its previous depth of as much as nine metres has now been reduced to just over a half-metre.

The Anzali Lagoon is registered as an endangered lagoon, and in 2010, Iran began a project in collaboration with the Japan International Cooperation Agency to save it.