Officials defend routine pond-clearing at Hangzhou's West Lake

A trending topic on the Chinese social media platform Sina Weibo claiming that 7 metric tons of bleaching powder would be spread over West Lake drew widespread public concern Thursday, prompting officials to clarify that the move is a routine measure to protect the city's iconic lotus plants.

Netizens questioned whether the disinfectant would pollute the water, harm wildlife, or disrupt tourism at the UNESCO World Heritage site.

In response, the Hangzhou West Lake Water Area Administration in Zhejiang province told China Daily that the operation is a long-standing annual practice. April marks a critical growth stage for lotus flowers, but rising spring temperatures also bring about pests, pathogens, and algae.

According to Yu Yangyang, head of the aquatic plant maintenance team, these factors compete with lotus plants for nutrients and can entangle delicate buds. Additionally, herbivorous fish often feed on new shoots; once damaged, the rhizomes are prone to rot, which can prevent blooming for the entire year.

To safeguard the shoots, the administration conducts an annual "pond-clearing" operation. This routine maintenance has been in place for nearly three decades.

The bleaching powder used consists primarily of calcium hypochlorite. Officials said the substance is a compliant disinfectant that helps eliminate pathogens and inhibit algae before decomposing naturally within one to two days.

Authorities emphasized that the 7,000 kilograms of powder will not be applied all at once. Instead, it is being used in stages across 24 designated lotus zones totaling approximately 10 hectares. To minimize disruption to visitors, all operations are conducted at night.

Strict procedures are followed during the process. Workers operate in pairs by boat, starting from the edges of enclosed zones to ensure the disinfectant is dispersed evenly and contained.

Lotus planting areas account for only about 1 percent of the lake’s total water surface and are isolated by protective nets. Before the operation begins, staff members raise the bottom of these nets to allow fish to swim out of the treatment zones, preventing chemical exposure and subsequent grazing on lotus shoots.

"The use of bleaching powder in this operation has minimal impact on native fish and bird species, and the entire process is environmentally safe," a staff member said.

The maintenance of the lake is a year-round effort. In spring, workers reinforce nets; in summer, they weed and thin plants; in autumn, enclosure nets are installed to help roots store nutrients; and in winter, withered plants are cleared to prepare for the next season.

This year's pond-clearing work began on the night of April 8 and is expected to conclude by April 12. Afterward, lotus buds will gradually emerge, with the first blooms of 2026 anticipated by late May.