ballastage

from The Century Dictionary.

• noun An old right of the admiralty in all the royal rivers of Great Britain to levy a rate for supplying ships with ballast.
• noun The toll paid for the privilege of taking ballast, as from a gravel-bed, etc.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Law) A toll paid for the privilege of taking up ballast in a port or harbor.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A toll paid for the privilege of taking up ballast in a port or harbour.