Nature drive puts city on green track

Environmental volunteer Lei Yueqin can recall what the Nanming River, which flows through Guiyang, Guizhou province, was like in the early 1950s. It was so pristine, she said, that people would use its water directly for drinking, cooking and washing.

"Kids would swim and catch fish in the river," the 81-year-old said.

But the waterway - a tributary of the Yangtze River - was quickly polluted by the increase in manufacturing emissions and household sewage that came after reform and opening-up brought economic growth.