[3] In the later 19th century, Zhenhai was protected from the sea by a dike about 3 miles (4.8 km) long, made of large blocks of hewn granite.

[1] Zhenhai has suffered severe long-term air pollution mainly emanating from the Ningbo Petro-Chemical Economic and Technical Development Zone built on its eastern coast.

[4][5] In late April, 2012, three million bees died in an orchard in Xiepu Town next to the Petro-Chemical Zone because of pollutants discharged by a chemical plant.

[7] From May 16 to 17, 2002, residents in Zhenhai launched protests against environmental degradation caused by the chemical industry, blocking the district's traffic on its main streets.

[8] In October, 2012, angry people staged demonstrations against a giant petro-chemical project scheduled by ZRCC and clashed with police.