Childhood idyll

When Liu, now an official with the Ulansuhai Nur administration, recalled his childhood, he described the lake as a consistent source of joy for him and his peers.

"After school, I seldom stayed home. I frequently went to swim in the lake. When I was thirsty, I drank the lake water directly," he said.

However, he saw the "fabulous environment" of the water begin to deteriorate in the 1990s, which he described as the time when industrialization and urbanization gained momentum.

In addition to runoff water from farmland in the Hetao irrigation area — which covers more than 730,000 hectares of arable land and is known as "the granary outside the Great Wall" — wastewater from the expanding urban areas and the booming industrial sector kept pouring into the low-lying lake.

The worst situation Liu can recall in Ulansuhai Nur came in 2008, when the lake was hit by an outbreak of algae which depleted the oxygen levels in the water. "The entire surface of the lake was blanketed by yellow algae. From a distance, it looked like a desert," he said.

It was at this time that Liu started working for a local tourism company. At the lake, he witnessed the deaths of large numbers of fish and noticed that the birds had started leaving.

"Nobody would swim in the lake anymore. When our excursion vessel moved, its screws churned up black water and a foul odor," he said. His company received so few tourists that he was on the brink of unemployment, he said.