Dead fish were seen drifting in Lake Qaraoun on the Litani River in Lebanon. According to Reuters

Tonnes of dead fish have ended up on the shores of a lake on Lebanon's Litani River, drenching a local village in a foul odour, in a tragedy attributed to contaminated waters.

Volunteers gathered rotting fish carcasses along the Qaraoun lake on Lebanon's longest canal, the Litani, where campaigners had already cautioned for ages about water contamination caused by sewage and waste.

Garbage pilings floated in the water among the dead fish. Swarms of flies were swarming near the reservoir, and thousands of fish were rotting in already contaminated water.

"This occurrence occurred on the lake's shore many days ago," Ahmad Askar, a local activist, said. "The fish began to swim up in unusual numbers... It is not acceptable."

At least 40 tonnes of dead fish have been discovered in just a few days, according to Askar and fishermen in Qaraoun. They urged the Litani River Authority to ascertain the source and pursue someone who was pouring pollutants into the lake.

The river authority announced this week that the fish were poisonous and infected with a virus, advising people to stop fishing along the Litani due to "an exacerbated tragedy that affects public health."

Because of the runoff, fishing in the lake has been forbidden since 2018. The reservoir was built in 1959 with a massive dam to store water for hydropower and irrigation.

Volunteers removed globs of sticky tar from beaches along the Lebanese coast last month after an oil spill that activists said would threaten marine life.

Ecological disasters are the last thing Lebanon wants as it deals with an unsettling financial crisis and the fallout from a massive explosion that destroyed Beirut's port last August.