Surrounded by marshes and brackish seepage lagoons, Haleji Lake was once the favorite destination of migratory birds that flew thousands of miles from Siberia to enjoy Pakistan's warm waters in harsh winters.

Located some 100 kilometers (62 miles) from Pakistan's commercial capital Karachi, the perennial freshwater lake is the South Asian country's first man-made water body.

Commissioned in 1942, the lake was aimed at supplying fresh water to the British troops stationed in Karachi during World War II.

Until a decade ago, the glistening blue waters of Haleji Lake would attract large numbers of migratory birds due to its rich biodiversity.

But, it currently offers a sorry sight, as reduced water levels, stagnant conditions, pollution, and other climate-driven factors have turned the lake into a gigantic pond of stagnant turbid water.

The lake would receive water from the mighty Indus River and has been one of the main sources of water supply to various parts of Karachi until 2018.

"There has been no inflow of fresh water from the Indus River into the lake over the past eight years, which has badly affected its health, in addition to disturbing the ecosystem," said Sohail Ahmed Khoso, an official of the Wildlife Department of Sindh province, for which Karachi serves as the capital.

Speaking to Anadolu on the occasion of World Wetlands Day, observed on Feb. 2 every year, Khoso said that the water inflow into the lake from the Indus River started to reduce in 2000 and was completely stopped in 2018.

The water body, which has been declared a wildlife sanctuary, would attract the largest number of migratory birds in winter until a few years ago.

Number of migratory birds reduced

A narrow metal road swung through a desolate terrain with wild vegetation to hit the western bank of the lake, once a bird watchers' paradise.

Spread over 18 square kilometers (6.9 sq miles), the lake is one of 19 Ramsar-certified water bodies in Pakistan.

Pakistan is a signatory to the 1971 Ramsar Convention on Wetlands of International Importance. It is named after the city of Ramsar in Iran.

The country's once-thriving wetlands, including Haleji Lake, long a sanctuary for millions of migratory birds fleeing Siberia’s brutal winters, are witnessing a disturbing decline in avian visitors.

These birds make the 4,500-kilometer (2,800-mile) journey from Siberia to India via the Indus Flyway, with stopovers at various lakes and water reservoirs in Pakistan.

Experts say a mix of prolonged drought, receding water levels, and growing habitat degradation is driving away these seasonal guests.

The Sindh province, a traditional favorite for migratory birds, has seen the most drastic decline. According to the Sindh Wildlife Department’s 2024-25 waterfowl count, the number of migratory birds fell sharply from 1.2 million in 2023 to 603,900 in 2024 and just 545,000 in 2025, a staggering drop of over 50% in two years.

According to Khoso, the number of migratory birds this year has reduced by 40% compared to 2025 due to shortages of fresh water, disturbance in the food chain, and pollution.

Last year, some 40,000 guest birds visited Haleji Lake following a gradual decline in their number.

"The current water levels in the lake are a result of the 2022 massive rains; otherwise, there has been no inflow or outflow of water over the past eight years," he maintained.

To cope with continued food shortages, he added, the Wildlife Department is artificially arranging foraging for guest birds, which, understandably, is not sufficient.

Endorsing the view, Rafiul Haq, a Karachi-based ecologist, feared that the number may further decline in the years to come due to a regular decline in the lake's health.

In the near past, he said, the over-body_abstraction and alternative water supply systems have destroyed the ecosystem of the country's "natural dams," like the Haleji Lake.

"They are natural dams, which need to be protected. But our priority is to build artificial water bodies, which seems illogical and disturbing for the overall biodiversity and perturbs the natural havens for migratory birds," he told Anadolu.

Haq called for the restoration of water inflow to the lake to restore its biodiversity.

Home to largest number of crocodiles

The reservoir is also home to the largest number of crocodiles in Pakistan.

According to Khoso, the lake hosts 400 to 500 crocodiles, which make up the largest population of the wild animal in the South Asian country.

Current estimates place the total crocodile population in Pakistan between 700 and 1,500.

In the 1970s, a pair of crocodiles was released into the lake to maintain ecological balance and the natural food chain. Their number soon grew to hundreds.

Crocodiles are important for ecological balance and the natural food chain, said Attaullah Pandrani, a Balochistan-based ecologist who has been associated with several habitat and species conservation projects.

Crocodiles help sustain the population of edible fish by eating carnivorous fish, especially those belonging to the catfish family.