Source : Webster's Revised Unabridged Dictionary (1913)

Water shrew \Wa"ter shrew`\ (Zo["o]l.)
   Any one of several species of shrews having fringed feet and
   capable of swimming actively. The two common European species
   ({Crossopus fodiens}, and {C. ciliatus}) are the best known.
   The most common American water shrew, or marsh shrew
   ({Neosorex palustris}), is rarely seen, owing to its
   nocturnal habits.

Source : WordNet®

water shrew
     n : any of several small semiaquatic shrews usually living near
         swift-flowing streams