The sandbank on which Scharhörn and Nigehörn lie is a European Union Natura 2000-designated bird sanctuary, tended to by the environmental group Verein Jordsand.

The island changed hands again in 1947, when it became part of the newly-drawn state of Lower Saxony, and again in 1969, when it was returned under a treaty to the control of Hamburg for the purpose of constructing a proposed deepwater port on Scharhörn and nearby Neuwerk.

The plans foresaw the construction of a 6,000 ha (15,000-acre) mound of land built from dredged sand, which was to be safe from the storm floods of the North Sea and connected to the mainland via a causeway from Scharhörn to Neuwerk to Cuxhaven.

For the people of Neuwerk and the nearby coastal villages, this was an important source of income, sometimes even legally acquired for rescue and salvage operations.

In the meantime, the oil slick covered an area of 1600 square kilometers and reached the islands of Amrum, Föhr, Sylt, Rømø and Fanø despite considerable attempts to combat it.