The Collaborative International Dictionary of English v.0.48:

Heelpath \Heel"path`\, n. [So called with a play upon the words
   tow and toe.]
   The bank of a canal opposite, and corresponding to, that of
   the towpath; berm. [U. S.]

         The Cowles found convenient spiles sunk in the
         heelpath.                                --The Century.
   [Webster 1913 Suppl.]