Still, dozens of people were seen jumping over the barricades or wriggling through police tape to go for a dip on a warm Monday afternoon.
A middle-aged man stood in the water singing an aria from a famous Peking Opera.
Some brought folding chairs, tables and small gas stoves to cook outside.
Since restaurants have been shuttered, only allowing takeout, and many housing blocks not permitting visitors, people have started picnicking on pavements.
“The guards come from time to time and chase us away,” said Reiner Zhang, a fashion designer who had spread her picnic mat on a street corner near the Liangma River.
“But we don’t care. People are frustrated with pay cuts and layoffs and we need to meet and vent,” she said.
Parents sat on the riverbank, eating watermelon, while children paddled along the shallow edges of the river.
“We bring the children here for some exercise,” said Niu Honglin, pointing to her seven-year-old son bobbing up and down in the river with his floaters.
“With parks closed, there are no places to play, but children start throwing tantrums if they are stuck at home all day doing online lessons.”
BRIEF RELIEF IN SHANGHAI
Old neighbourhoods in the heart of Beijing, normally bustling warrens filled with hawkers, tourists and rickshaw drivers, have also been closed.
But a couple posed for wedding photos in front of the old drum tower on Monday, while on a nearby street retirees gathered to play mahjong, flouting strict social distancing rules.
“We come here after lunch every day, and play until the sun goes down,” said a retired municipal worker who only offered his last name Zao.
“We’ve done it for years and the pandemic won’t stop us.”
In Shanghai, residents are slowly emerging from the other side of a lockdown during which millions were banned from stepping out of their homes.
The mood was festive in the central Jing’an district on Wednesday outside one apartment compound where residents were finally permitted to step outside – for only two hours – after 55 days indoors.
A masked quartet of friends toasted their brief freedom with champagne, while a group of older women put on their Sunday best for a long-awaited stroll through the neighbourhood.
A barber in protective gear gave customers haircuts in a makeshift roadside salon, as most hairdressers in the city remained shut.