Source : Webster's Revised Unabridged Dictionary (1913)

Conservancy \Con*serv"an*cy\, n.
   Conservation, as from injury, defilement, or irregular use.

         [An act was] passed in 1866, for vesting in the
         Conservators of the River Thames the conservancy of the
         Thames and Isis.                         --Mozley & W.

Source : WordNet®

conservancy
     n 1: a commission with jurisdiction over fisheries and navigation
          in a port or river
     2: the official conservation of trees and soil and rivers etc.