How far from shore must a ballast water exchange be completed?

The requirement for ballast water exchange is established to minimize the risk of introducing non-native species into coastal ecosystems. The correct distance for ballast water exchange is no less than 200 nautical miles from shore. This regulation is based on scientific evidence that indicates that organisms are less likely to survive the transit in open ocean conditions, making 200 nautical miles a suitable threshold to protect coastal environments.

In this context, conducting the exchange at this distance allows for the dilution of any potential harmful organisms that may be present in the ship's ballast water, ensuring that the water taken on at sea poses a reduced risk to the marine biodiversity of coastal waters when discharged later.

The other distances listed do not provide sufficient assurance of reducing the transfer of potentially invasive species, as they fall within regions where organisms might still be viable and could affect local ecosystems. As a result, the 200 nautical mile distance is a regulatory standard that helps to safeguard marine environments while supporting safe maritime operations.