A Sha Tin district council member said a multi-departmental emergency plan was activated on Tuesday after the Lower Shing Mun Reservoir’s water level reached a critical threshold.

The Home Affairs Department issued a public warning urging residents to avoid both sides of the Shing Mun River.

The department said it had notified residents in nearby housing estates, such as Mei Lam Estate, May Shing Court, Mei Chung Court and Granville Garden. It said it had also alerted the Sha Tin District Office, Drainage Services Department and the police based on an emergency mechanism.

"The Home Affairs Department has actually activated its emergency notification system. We have informed all potentially affected housing estates and villages through established channels, like care teams and property management offices," Sha Tin district councillor Calvin Tang told RTHK.

"We secured the area... the police on-site to cordon all and close all public access to the riverbanks, including the pedestrian walkways and cycling tracks to prevent accidents.

"The Drainage Services Department has deployed its emergency response teams to patrol the entire district, especially known flooding blackspots to clear all blockages and carry out urgent repairs to ensure storm water can be discharged effectively.

"The (Water Supplies Department) began diverting some of the water flow from lower Shing Mun River to other reservoirs to relieve pressure and slow down the rate at which the water level is rising."

Tang said that large-scale evacuation was unnecessary, noting similar threshold levels have occurred during past extreme weather events like Typhoon Mangkhut in 2018.

He added that the government has a comprehensive multi-project strategy to bolster Sha Tin’s long-term flood resilience.

"Like in the mainstream flood storage, there is a major project that is already under way to construct such a storage tank in Sha Tin Park. The tank will have a capacity of around 8,600 cubic metres and will temporarily store excess rainwater during storms. It will be available in 2029," he said.

"The (Drainage Services Department) has some downstream improvements. It includes some regular clearing of the river channel to maintain its depth and the capacity to ensure the draining outlets are clear.

"There is a plan of 1.8 kilometres new flood walls being constructed among the Shing Mun River to provide extra physical barrier against the high water levels."