NOUN (3)

1. a fee charged for passage through a lock in a canal or waterway;

2. a system of locks in a canal or waterway;

3. passage through a lock in a canal or waterway;

The Collaborative International Dictionary of English v.0.48:

Lockage \Lock"age\, n.
   1. Materials for locks in a canal, or the works forming a
      lock or locks.
      [1913 Webster]

   2. Toll paid for passing the locks of a canal.
      [1913 Webster]

   3. Amount of elevation and descent made by the locks of a
      canal.
      [1913 Webster]

            The entire lock will be about fifty feet. --De Witt
                                                  Clinton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lockage
    n 1: a fee charged for passage through a lock in a canal or
         waterway
    2: a system of locks in a canal or waterway
    3: passage through a lock in a canal or waterway